ASTM D121-15(2024)

Standard Terminology of Coal and Coke

SCOPE
1.1 This terminology defines the technical terms used in standards that are the responsibility of Committee D05 on Coal and Coke. The terms are used in:  
1.1.1 The sampling of coal and coke under conditions required for most commercial and technical purposes related to coal and coke.  
1.1.2 Bias and related statistical testing,  
1.1.3 The description of coal, both visually in the field and microscopically in the laboratory,  
1.1.4 Chemical and physical analyses of coal and coke,  
1.1.5 Classification of coal, and  
1.1.6 Certain other related practices and guides applicable to the coal and coke industries.  
1.2 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 29-Feb-2024
• ICS: 01.040.73 - Mining and minerals (Vocabularies)
• ICS: 01.040.75 - Petroleum and related technologies (Vocabularies)
• ICS: 73.040 - Coals
• ICS: 75.160.10 - Solid fuels
• Technical Committee: D05 - Coal and Coke
• Drafting Committee: D05.24 - Statistics

Relations

• Replaces: ASTM D121-15 - Standard Terminology of Coal and Coke
• Effective Date: 01-Mar-2024
• Refers: ASTM D7582-24 - Standard Test Methods for Proximate Analysis of Coal and Coke by Macro Thermogravimetric Analysis
• Effective Date: 01-Apr-2024
• Refers: ASTM D3176-24 - Standard Practice for Ultimate Analysis of Coal and Coke
• Effective Date: 01-Apr-2024
• Refers: ASTM D3176-15(2023) - Standard Practice for Ultimate Analysis of Coal and Coke
• Effective Date: 01-Dec-2023
• Referred By: ASTM D6349-21 - Standard Test Method for Determination of Major and Minor Elements in Coal, Coke, and Solid Residues from Combustion of Coal and Coke by Inductively Coupled Plasma-Atomic Emission Spectrometry
• Effective Date: 01-Mar-2024
• Referred By: ASTM D2799-23 - Standard Test Method for Microscopical Determination of the Maceral Composition of Coal
• Effective Date: 01-Mar-2024
• Referred By: ASTM D7348-21 - Standard Test Methods for Loss on Ignition (LOI) of Solid Combustion Residues
• Effective Date: 01-Mar-2024
• Referred By: ASTM D6542-05(2018)e1 - Standard Practice for Tonnage Calculation of Coal in a Stockpile
• Effective Date: 01-Mar-2024
• Referred By: ASTM D6316-17 - Standard Test Method for Determination of Total, Combustible and Carbonate Carbon in Solid Residues from Coal and Coke
• Effective Date: 01-Mar-2024
• Referred By: ASTM D7430/D7430M-22 - Standard Practice for Mechanical Sampling of Coal
• Effective Date: 01-Mar-2024
• Referred By: ASTM D4208-19 - Standard Test Method for Total Chlorine in Coal by the Oxygen Vessel Combustion/Ion Selective Electrode Method
• Effective Date: 01-Mar-2024
• Referred By: ASTM D4596-22 - Standard Practice for Collection of Channel Samples of Coal in a Mine
• Effective Date: 01-Mar-2024
• Referred By: ASTM D3172-13(2021)e1 - Standard Practice for Proximate Analysis of Coal and Coke
• Effective Date: 01-Mar-2024
• Referred By: ASTM D7708-23a - Standard Test Method for Microscopical Determination of the Reflectance of Vitrinite Dispersed in Sedimentary Rocks
• Effective Date: 01-Mar-2024
• Referred By: ASTM D8247-19 - Standard Test Method for Determination of Total Fluorine and Total Chlorine in Coal by Oxidative Pyrohydrolytic Combustion Followed by Ion Chromatography Detection
• Effective Date: 01-Mar-2024

Overview

ASTM D121-15(2024) - Standard Terminology of Coal and Coke is a key international standard developed by ASTM Committee D05, dedicated to unified and precise technical language for the coal and coke industries. This standard defines terminology relevant to the sampling, analysis, classification, and description of coal and coke, supporting commercial and technical applications. The standard aligns with internationally recognized principles of standardization as established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

By providing standardized definitions, ASTM D121-15(2024) facilitates effective communication, regulatory compliance, and consistent analysis across the supply chain, including mining, processing, laboratory analysis, and environmental compliance for coal and coke.

Key Topics

• Sampling Methodologies: Terminology related to sampling procedures for coal and coke to ensure representative and unbiased samples for commercial and technical analyses.
• Statistical and Bias Testing: Definitions supporting the design and interpretation of bias and statistical tests in coal and coke sample analysis.
• Material Description: Terms for both field and laboratory descriptions, enabling accurate characterization by visual and microscopic techniques.
• Chemical and Physical Analysis: Standardized terminology for conducting and reporting chemical and physical tests, ensuring comparability and repeatability.
• Coal Classification: Definitions supporting the classification of coal by rank, composition, and other relevant industry criteria.
• Industry Practices: Guidance on terms used in industry practices, guides, and sampling standards relevant to coal and coke production, testing, and classification.

Applications

Adopting ASTM D121-15(2024) terminology brings practical value to several industry sectors and activities:

• Laboratories: Enables precise communication of test methods (e.g., proximate/ultimate analysis, moisture and ash content, calorific value determination) and results, minimizing misinterpretation.
• Coal and Coke Mining Operations: Supports consistent description of coal seams, core samples, and processing outputs, improving data quality for exploration and reporting.
• Quality Control and Assurance: Facilitates standardized reporting for traded coal and coke products, ensuring alignment with contractual and regulatory requirements.
• Regulatory Compliance: Harmonizes terminology used in environmental and safety reporting, supporting compliance with international trade and environmental standards.
• Education and Training: Provides a foundational vocabulary for developing training materials and competency development for professionals in the coal and coke industry.
• Research and Development: Assists in the dissemination and clarity of technical publications and innovation in coal characterization, beneficiation, and utilization.

Related Standards

ASTM D121-15(2024) references and complements numerous specialized coal and coke standards, including:

• ASTM D388: Classification of Coals by Rank
• ASTM D3172: Practice for Proximate Analysis of Coal and Coke
• ASTM D3174/D7582: Test Methods for Ash and Proximate Analysis
• ASTM D3180: Practice for Calculating Analyses from As-Determined to Different Bases
• ASTM D3302: Total Moisture in Coal
• ASTM D4371: Washability Characteristics of Coal
• ASTM D4749: Sieve Analysis and Coal Size Designation
• ASTM D5865: Gross Calorific Value Determination
• ASTM D5061: Microscopical Determination of Metallurgical Coke Components
• ASTM D5114: Laboratory Froth Flotation of Coal
• ASTM D5192: Collection of Core Coal Samples

For the most current list and access to referenced standards, visit ASTM International.

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By using ASTM D121-15(2024) for terminology of coal and coke, organizations operating in the coal supply chain can enhance clarity, consistency, and quality in technical communication and documentation, benefiting research, commercial transactions, and regulatory compliance alike.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D121 − 15 (Reapproved 2024)
Standard Terminology of
Coal and Coke
This standard is issued under the fixed designation D121; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3172 Practice for Proximate Analysis of Coal and Coke
D3173 Test Method for Moisture in the Analysis Sample of
1.1 This terminology defines the technical terms used in
Coal and Coke
standards that are the responsibility of Committee D05 on Coal
D3174 Test Method for Ash in the Analysis Sample of Coal
and Coke. The terms are used in:
and Coke from Coal
1.1.1 The sampling of coal and coke under conditions
D3175 Test Method for Volatile Matter in the Analysis
required for most commercial and technical purposes related to
Sample of Coal and Coke
coal and coke.
D3176 Practice for Ultimate Analysis of Coal and Coke
1.1.2 Bias and related statistical testing,
D3180 Practice for Calculating Coal and Coke Analyses
1.1.3 The description of coal, both visually in the field and
from As-Determined to Different Bases
microscopically in the laboratory,
D3302 Test Method for Total Moisture in Coal
1.1.4 Chemical and physical analyses of coal and coke,
D4371 Test Method for Determining the Washability Char-
1.1.5 Classification of coal, and
acteristics of Coal
1.1.6 Certain other related practices and guides applicable
to the coal and coke industries. D4749 Test Method for Performing the Sieve Analysis of
Coal and Designating Coal Size
1.2 This international standard was developed in accor-
D5061 Test Method for Microscopical Determination of the
dance with internationally recognized principles on standard-
Textural Components of Metallurgical Coke
ization established in the Decision on Principles for the
D5114 Test Method for Laboratory Froth Flotation of Coal
Development of International Standards, Guides and Recom-
in a Mechanical Cell
mendations issued by the World Trade Organization Technical
D5192 Practice for Collection of Coal Samples from Core
Barriers to Trade (TBT) Committee.
D5263 Test Method for Determining the Relative Degree of
2. Referenced Documents
Oxidation in Bituminous Coal by Alkali Extraction
D5515 Test Method for Determination of the Swelling
2.1 ASTM Standards:
Properties of Bituminous Coal Using a Dilatometer
D388 Classification of Coals by Rank
D5865 Test Method for Gross Calorific Value of Coal and
D1412 Test Method for Equilibrium Moisture of Coal at 96
to 97 Percent Relative Humidity and 30 °C Coke
D6316 Test Method for Determination of Total, Combustible
D1857 Test Method for Fusibility of Coal and Coke Ash
D2013 Practice for Preparing Coal Samples for Analysis and Carbonate Carbon in Solid Residues from Coal and
D2234/D2234M Practice for Collection of a Gross Sample Coke
of Coal D7430 Practice for Mechanical Sampling of Coal
D2639 Test Method for Plastic Properties of Coal by the D7582 Test Methods for Proximate Analysis of Coal and
Constant-Torque Gieseler Plastometer
Coke by Macro Thermogravimetric Analysis
D2798 Test Method for Microscopical Determination of the
Vitrinite Reflectance of Coal
3. Terminology
air-dried moisture—this term has been used inappropriately
This terminology is under the jurisdiction of ASTM Committee D05 on Coal
to refer to both residual moisture and air-dry loss. Because of
and Coke and is the direct responsibility of Subcommittee D05.24 on Statistics.
the potential for confusion, this term shall not be used.
Current edition approved March 1, 2024. Published March 2024. Originally
approved in 1921. Last previous edition approved in 2015 as D121 – 15. DOI:
10.1520/D0121-15R24.
air drying, n—a process of partial drying of coal to bring its
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
moisture near to equilibrium with the atmosphere in the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
room in which further reduction and division of the sample
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website. will take place.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D121 − 15 (2024)
air-dry loss, n— in coal, the loss in mass, expressed as a bed moisture—synonym for inherent moisture.
percentage, resulting from each air-drying stage or the sum
beehive coke—See beehive coke under coke.
of all sequential air-drying stages in which the results from
binder phase, n— as used in Test Method D5061, a continuous
each stage are adjusted to the as-received basis.
solid carbon matrix formed during the thermoplastic defor-
DISCUSSION—Air-dry loss is neither a standard state nor a character-
mation of those coal macerals that become plastic during
istic property of a coal. Air drying only removes water that can
evaporate at or near ambient laboratory conditions, leaving in the coal carbonization.
some fraction of the inherent moisture that is more tightly bound in the
DISCUSSION—The binder phase material is formed from the thermo-
pores (residual moisture). Different laboratory environments or differ-
plastic deformation of reactive (vitrinite and liptinite) and semi-inert
ent drying temperatures or both will result in significant differences in
(semifusinite) coal macerals of metallurgical bituminous coals. During
air-dry loss and residual moisture. D3302 thermoplasticity, the inert coal maceral and mineral are partly or wholly
incorporated into the binder phase. Also, most of the coke pores are
agglomerating, adj—as applied to coal, the property of
located in the binder phase. D5061
softening when it is heated to above about 400 °C in a
bituminous class—See bituminous class under rank.
nonoxidizing atmosphere, and then appearing as a coherent
mass after cooling to room temperature.
boghead coal—See boghead coal under coal.
bone coal—See bone coal under coal.
alginite—See alginite under maceral.
borehole, n—the circular hole through soil and rock strata
analysis sample—See analysis sample under sample.
made by boring.
angle of repose, n—the greatest angle, measured from
horizontal, attained by a coal so that material on the sides or
bottomsize, nominal— for the purpose of Test Method D4749,
top of the inverted cone or trench created in car top sampling
the sieve designating the lower limit or bottomsize shall be
remains stable, that is, will not shift or slide. Coal size and
that sieve of the series given in the Standard Series of Sieves
moisture content are contributing factors to this angle. In all
section with the largest openings through which passes a
cases, the coal shall be dug so that the physical angle is less
total of less than 15 % of the sample. This defined bottom-
than the angle of repose.
size is not to be confused with the size of the smallest
particles in the lot.
anisotropic, adj—as used in Test Method D5061, exhibiting
DISCUSSION—(Warning—In the case of a commercial, double-
optical properties of different values when viewed with an
1 3
screened product, for example, 37.5 by 9.5 mm (1 ⁄2 by ⁄8 in.), this
optical microscope having mutually exclusive polarized
designation may not be valid. In such commercial or contractual
light, for example, crossed nicols. D5061
situations, the amount of allowable material smaller than the bottom-
size (for example, 9.5 mm) must be specified by the contract under
anthracite—See anthracite under rank.
which the coal is bought and solid.) D4749
anthracitic class—See anthracitic class under rank.
apparent rank, n—of coal, the rank designation obtained on
briquette, n—a cylindrical block composed of granulated coal
samples other than channel samples, but otherwise conform-
or coke particles compressed and embedded with an epoxy
ing to procedures of Classification D388.
binder.
as-analyzed moisture—synonym for as-determined moisture.
by-product coke—See by-product coke under coke.
C test, n—a standard statistical test for homogeneity of
as-determined basis—See as-determined basis under report-
variance.
ing bases.
ash, n—inorganic residue remaining after ignition of combus-
calorific value, n—the heat of combustion of a unit quantity of
tible substances, determined by definite prescribed methods.
a substance.
DISCUSSION—Ash need not be identical, in composition or quantity,
DISCUSSION—It is expressed in ASTM test methods in British thermal
with the inorganic substances present in the material before ignition. In
units per pound (Btu/lb). Calorific value can also be expressed in
the case of coal and coke, the methods used shall be those prescribed
calories per gram (cal/g) or in the International System of Units, joules
in Test Method D3174 or D7582.
per gram (J/g), when required. D5865
as-mined coal—for the purpose of Test Method D4749, same
calorimeter, n— as used in Test Method D5865, the bomb and
as run-of-mine (ROM) coal. D4749
its contents, the calorimeter vessel with stirrer, the water in
which the bomb is immersed, and the portions of the
as-received basis—See as-received basis under reporting
bases. D3180 thermometer and the ignition leads within the calorimeter
vessel. D5865
as-shipped or produced coal—for the purpose of Test Method
D4749, raw or prepared coal in any state or condition at
calorimeter jacket, n—the insulating medium surrounding the
which it leaves the mine property or loading facility. D4749
calorimeter.
attrital coal—See attrital coal under coal.
cannel coal—See cannel coal under coal.
auger increment, n—the retained portion of one extraction
carbonate carbon, n—the carbon content present in the solid
operation of the auger.
products derived from the combustion or reaction of coal,
banded coal—See banded coal under coal.
coal by-products, or coke as carbonates and which is
basis—See reporting bases. noncombustible in standard industry practice. D6316
D121 − 15 (2024)
no interbedded vitrain. Nonbanded coal also is attrital coal but is not
carbon form, n— as used in Test Method D5061, microscopi-
usually referred to as such. In contrast to the coarser and more variable
cally distinguishable carbonaceous textural components of
texture of attrital coal in banded coal, nonbanded coal is notably
coke, but excluding mineral carbonates.
uniform and fine in texture, being derived from size-sorted plant debris.
DISCUSSION—Carbon forms are recognized on the basis of their
The luster of attrital coal, which ranges from bright (but less than that
reflectance, anisotropy, and morphology. They are derived from the
of associated vitrain) to dull, is commonly used to describe and
organic portion of coal and can be anisotropic or isotropic. D5061
characterize attrital coal. As an alternative, some petrographers subdi-
vide attrital coal into clarain and durain. Clarain has bright luster and
caves or washouts, n—zones of increased hole diameter
silky texture, being finely striated parallel to the coal bedding. Durain
caused by rock fragments that fall from the walls of a
has dull luster and sometimes is referred to as dull coal. Similarly, coal
borehole and can block the hole or contaminate the cuttings
consisting of vitrain or clarain or a mixture of the two is sometimes
and which erode or abrade the sidewall of the borehole by
referred to as bright coal.
the action of the drilling. These zones can affect the accuracy
banded coal, n—coal that is visibly heterogeneous in
of certain geophysical logs (especially density). Corrections
composition, being composed of layers of vitrain and attrital
to other geophysical logs can be made if a caliper log is
coal, and, commonly, fusain.
available. The most common causes of caves or washouts
boghead coal, n—nonbanded coal in which the liptinite (the
include soft or fractured lithologies, the presence of water-
waxy component) is predominantly alginite.
producing zones, and the downhole pressure of the drilling
medium (fluid or air) that often causes differential erosion of
bone coal, n—impure coal that contains much clay or other
various strata within the borehole.
fine-grained detrital mineral matter.
chance error, n—error that has equal probability of being cannel coal, n—nonbanded coal in which the liptinite is
positive or negative. The mean of the chance errors resulting predominantly sporinite.
from a series of observations tends toward zero as the DISCUSSION—Transitions between cannel and boghead, that is, coals
containing both types of liptinite, are also known. Microscopic exami-
number of observations approaches infinity.
nation is essential for differentiation of the two kinds of nonbanded coal
circular anisotropic phase, n—as used in Test Method D5061, and their transitions.
a group of binder-phase anisotropic carbon textures that are
fusain, n—coal layers composed of chips and other frag-
distinguished by approximately circular domains (that is
ments in which the original form of plant tissue structure is
length equals width) and composed of fine circular (0.5 to
preserved; commonly has fibrous texture with a very dull
1.0 μm), medium circular (1.0 to 1.5 μm), and coarse circular
luster.
(1.5 to 2.0 μm) size categories. D5061
DISCUSSION—Fusain is very friable and resembles charcoal.
Commonly, it is concentrated in bedding layers or lenses that form
cleat, n—the joint system of coal seams, usually oriented
planes of weakness in coal and thus is often exposed on bedding
normal or nearly normal to the bedding.
surfaces of broken coal. The many pores (cell cavities and cracks) of
DISCUSSION—Cleat is most commonly found in bituminous coal,
fusain are sometimes filled with mineral matter.
being most prominently developed in vitrain bands and bright layers.
impure coal, n—coal having 25 weight % or more, but less
Some cleat, especially the more widely separated joints, extend through
all or a large part of the seam. Cleat surfaces are commonly coated with than 50 weight %, of ash on the dry basis.
minerals such as calcite, kaolinite, and pyrite.
DISCUSSION—Bone coal with more than 50 weight % ash is properly
called coaly or carbonaceous shale or siltstone. Types of impure coal
coal, n—a brown to black combustible sedimentary rock (in the
other than bone coal and mineralized coal sometimes occur, for
geological sense) composed principally of consolidated and
example, sandy coal.
chemically altered plant remains.
lithotype, n— any of the constituents of banded coal: vitrain,
DISCUSSION—Conditions required for formation of coal are believed
fusain, clarain, durain, or attrital coal or a specific mixture of
to include accumulation of plant remains and their partial decomposi-
tion under moist conditions, followed by sedimentary burial and two or more of these.
subjection to increased pressure and temperature according to the
mineralized coal, n—impure coal that is heavily impregnated
geological history of the seam. Coals exhibit a wide range of properties
with mineral matter, either dispersed or discretely localized
as a result of differences in the kinds and relative amounts of different
along cleat joints or other fissures. Pyritic or calcareous
plant materials and intermixed mineral matter, the amount of alteration
of the plant remains achieved before burial, and especially the degree mineralized coal is most common.
of physical and chemical alteration after burial. See Classification D388
nonbanded coal, n—consistently fine-granular coal essen-
for classification of coal in accordance with its degree of alteration or
tially devoid of megascopic layers.
rank. The moisture content and the kind, amount, and mode of
DISCUSSION—Nonbanded coal may be interbedded with common
occurrence of mineral matter also vary greatly.
banded coal, or form a discrete layer at the top or at the bottom of the
attrital coal, n—the ground mass or matrix of banded coal in
seam, or may compose the entire seam. It is formed from natural
which vitrain and, commonly, fusain layers as well, are
accumulations of finely comminuted plant detritus and commonly
embedded or enclosed.
includes a significant amount and variety of remains of pollen grains,
DISCUSSION—Layers in banded coal, often referred to as bands, are spores, planktonic algae, wax and resin granules, as well as other
commonly 1 to 30 mm thick. Attrital coal in banded coal is highly fragments of plants. These materials, containing markedly higher
varied in composition and appearance, its luster varying from a amounts of volatile matter than vitrain and some other attrital
brilliance nearly equal to that of the associated vitrain to nearly as dull components, are more abundant in this variety of coal than they are in
as fusain; it exhibits striated, granulose, or rough texture. In a few common types of banded coal. Also, nonbanded coal may contain more
cases, relatively thick layers of such attrital coal are found that contain disseminated detrital mineral matter, chiefly clay, than associated
D121 − 15 (2024)
banded coals, and in the field it may be difficult to distinguish from DISCUSSION—Coke pores are considered to be nearly spherical-
bone coal. Nonbanded coal is much less common than banded coal in shaped voids created by the entrapment of gaseous volatiles during the
North America. solidification of thermoplastic coal. However, other types of voids can
be distinguished in coke that include fractures or cracks, interconnected
vitrain, n—shiny black bands, thicker than 0.5 mm, of
and elongated pores, and the open cell lumens of fusinite and
subbituminous and higher rank banded coal.
semifusinite. The size and shape of the voids are coal rank and grade,
DISCUSSION—Vitrain, attributed to the coalification of relatively large
and to some degree, process dependent. Pore sizes vary from tens of
fragments of wood and bark, may range up to about 30 mm (approxi-
angstroms to tens of millimetres in any given coke. D5061
mately 1 in.) thick in eastern North American coals, but may be much
thicker in the younger western deposits. Vitrain is commonly traversed
coke reactivity, n—as used in Test Method D5061, a measure
by many fine cracks oriented normal to the banding.
of the mass loss when coke, held at a designated
In lignite, the remains of woody material lack the shiny luster of
temperature, is contacted with gaseous carbon dioxide over
vitrain in the higher rank coals and may instead be called previtrain. It
a specific time interval. D5061
is differentiated from attrital bands of lignite by its smoother texture,
often showing the grain of wood. Previtrain may be several inches
coke wall, n—as used in Test Method D5061, a predominantly
thick.
carbonaceous layer that encloses a coke pore and which is a
coal seam, n—the stratum, layer, or bed of coal that lies
structural element and essence of coke. D5061
between two other rock layers whose compositions differ
collector, n—a reagent used in froth flotation to promote
significantly from that of coal.
contact and adhesion between particles and air bubbles.
coal washability, n—the determination of the theoretical limits
D5114
for the removal of mineral impurities from coal by benefi-
combustible carbon, n—carbon content remaining in the solid
ciation processes that rely on specific gravity separations.
products derived from the combustion or reaction of coal,
D4371
coal by-products, or coke, exclusive of carbonate in any
coarse coal, n—that portion of a coal sample being subjected
form. D6316
to a washability study that is larger than a specific predeter-
mined particle size, generally between 2.36 mm (No. 8 USA
combustibles, n—the value obtained by subtracting the dry
Standard Sieve Series) and 9.5 mm ( ⁄8 in.) round in diameter.
weight (in percent) of the ash (as determined in Test Method
DISCUSSION—This same particle size breakpoint should then be used
D3174) from 100 % representing original weight of ana-
in subsequent washability studies of the same material sampled from
lyzed sample. D5114
the same location for the same application. This breakpoint is deter-
mined by the analyst or the person designing the test procedure as the
concentrate, n—the froth product recovered in coal froth
point that best suits the application. This coarse-coal fraction may be
flotation. D5114
further sieved (generally by dry sieving) to produce additional size
fractions, each of which may be processed through the desired specific
concretion, n—in a geological sense, a mass of mineral matter
gravity solutions. D4371
found in rock of a composition different from its own and
produced by deposition from aqueous solution in the rock.
coke—a carbonaceous solid produced from coal, petroleum, or
other materials by thermal decomposition with passage
conditioning agents, n—all chemicals that enhance the perfor-
through a plastic state.
mance of the collectors or frothers. Conditioning agents
beehive coke, n—coke manufactured in beehive, rectangular,
change the characteristics of the surface of the minerals or
or similar forms of ovens in a horizontal bed, where heat for
the environment. There are many subgroups according to
the coking process is secured by combustion within the oven
their function: activators, depressants, emulsifiers,
chamber.
dispersants, flocculants, chelating reagents, froth
depressants, pH modifiers, etc. D5114
by-product coke, n—coke manufactured with attendant re-
covery of by-products, in ovens that are heated externally.
core, n—in drilling, a cylindrical section of rock (coal) that is
coke breeze, n—the fine screenings from crushed coke or
usually 5 to 10 cm in diameter, taken as part of the interval
from coke as taken from the ovens, of a size varied in local
penetrated by a core bit and brought to the surface for
practice but usually passing a 12.7 mm ( ⁄2 in.) or 19.0 mm
geologic examination, representative sampling and labora-
( ⁄4 in.) screen opening.
tory analyses.
dry coke, n—a laboratory term applied to coke that has been
core barrels, n—two nested tubes above the bit of a core drill,
dried to constant weight in accordance with definite prescribed
the outer rotating with the bit, the inner receiving and
methods.
preserving a continuous section or core of the material
DISCUSSION—The methods used shall be those for the determination
penetrated. The following two types of inner barrels are
of moisture prescribed in Test Method D3302. In the case of lump coke,
commonly used.
the temperature shall be not less than 104 °C nor more than 200 °C; in
the case of coke passing a 250 μm (No. 60) sieve, the temperature shall
split-tube barrel, n—a type of inner barrel consisting of two
be not less than 104 °C nor more than 110 °C for a period of 1 h.
longitudinal halves of pipe bound together by reinforced tape at
coke pore, n—as used in Test Method D5061, a microscopi- intervals along the barrel length that allows easy access to a
cally distinguishable void that is a structural element of relatively intact core (by cutting the tape). (This is the preferred
coke. D5061 barrel type for coal exploration, where available.)
D121 − 15 (2024)
solid-tube barrel, n—a type of inner barrel consisting of a easily oxidized coals, n—low rank coals such as subbitumi-
single solid-walled length of pipe in which removal of the core nous or lignitic coals. D3302
is accomplished by mechanical or hydraulic pressure at one
energy equivalent, heat capacity, or water equivalent,
end of the pipe thus extruding the core onto a core tray. (The
n—the energy required to raise the temperature of the
core is likely to be less intact than when a split-tube barrel is
calorimeter an arbitrary unit. This is the quantity that, when
used.)
multiplied by the corrected temperature rise, then adjusted
for extraneous heat effects, and divided by the weight of the
core sample, n—that part of a core of rock or coal obtained so
as to represent accurately a thickness of a unit penetrating by sample, gives the gross calorific value.
DISCUSSION—Energy units for quantities listed throughout this test
drilling. D5192
method are such that the number of energy units per gram of sample
corrected temperature rise, n—the temperature of the corresponds exactly to the number of British thermal units per pound of
sample. For brevity, these are referred to as British thermal units. The
calorimeter, caused by the process that occurs inside the
actual energies are smaller than those stated by the ratio of the number
bomb; that is, the observed temperature change corrected for
of pounds per gram (1/453.59). The energy equivalent of the calorim-
various effects.
eter has the units (British thermal units per pound) times (grams per
DISCUSSION—Temperature is measured in either degrees Celsius or
degree). Time is expressed in minutes. Mass is expressed in grams.
degrees Fahrenheit. Thermometer corrections should be applied. Tem-
D5865
peratures may be recorded in ohms or other arbitrary units instead of
degrees. Consistent units must be used in standardization and the actual
equilibrium, n—condition reached in air drying in which
calorific value determination. If arbitrary units other than degrees
change in weight of the sample, under conditions of ambient
Celsius or Fahrenheit are used, the temperature interval over which all
temperature and humidity, is no more than 0.1 % ⁄h or
tests are made must not vary so much that an error greater than
0.05 % ⁄ ⁄2 h. D3302
0.001 °C would be caused. D5865
equilibrium moisture basis—See equilibrium moisture basis
cutinite—See cutinite under maceral.
under reporting bases.
depositional carbon, n—as used in Test Method D5061, a
error—difference of an observation from the best obtainable
group of carbon forms that are formed from cracking and
estimate of the true value.
nucleation of gas-phase hydrocarbon molecules during coal
carbonization. D5061
exinite—See exinite under maceral.
filler phase, n— as used in Test Method D5061, a discontinu-
pyrolytic carbon, n—as used in Test Method D5061, an
anisotropic carbon form that is formed by the deposition of ous solid formed from coal macerals and minerals that do not
deform thermoplastically during carbonization. D5061
carbon parallel to an inert substrate causing the resulting
texture to appear ribbon-like. D5061 DISCUSSION—The filler phase material is formed from coal macerals
that are inert with respect to development of thermoplasticity
sooty carbon, n—as used in Test Method D5061, an isotropic
(inertinite), the inorganic components of coal (minerals), as well as
carbon form comprised of approximately spherical particles of
normally reactive coal entities that are noncoking or have been
less than 1-μm diameter sometimes referred to as combustion
rendered inert by thermal oxidation, natural weathering, or brecciation.
These inert materials possess their original morphologies, but their
black. D5061
reflectance and chemical properties have been altered prior to or during
spherulitic carbon, n—as used in Test Method D5061, a
carbonization. D5061
spherical anisotropic carbon form sometimes referred to as
fine coal, n—that portion of a coal sample being subject to a
thermal black that is formed by the deposition of carbon
washability study that is smaller than the predetermined
concentrically around a nucleus. D5061
particle size, generally between 2.36 mm (No. 8 USA
divided sample—See divided sample under sample.
Standard Sieve Series) and 9.5 mm ( ⁄8 in.) round in
dilatation, percent (%D), n—the maximum recorded height
diameter, which is specified in Test Method D4371.
of char expressed as a percentage, based on an initial coal
DISCUSSION—This same particle size breakpoint should then be used
pencil height of 60 mm. D5515
in subsequent washability studies of the same material samples from
the same location for the same application. This breakpoint is deter-
domain, n—as used in Test Method D5061, a region of
mined by the analyst or the person designing the test procedure as the
anisotropy in a carbon form that is distinctively marked by
point that best suits the application. This fine-coal fraction may be
its isochromatic boundary and cleavage. D5061
further sieved (generally by wet sieving) to produce additional size
fractions, each of which is processed through the desired specific
dry, ash-free basis—See dry, ash-free basis under reporting
gravity solutions. D4371
bases.
fixed carbon, n— in the case of coal, coke, and bituminous
dry basis—See dry basis under reporting bases.
materials, the solid residue other than ash, obtained by
dry coke—See dry coke under coke.
destructive distillation, determined by definite prescribed
dry sieving—for the purpose of Test Method D4749, the test
methods.
method for the sieving of coal after the sample has been
DISCUSSION—It is made up principally of carbon but may contain
airdried under prescribed conditions; this is generally used
appreciable amounts of sulfur, hydrogen, nitrogen, and oxygen.
when testing with coal particles larger than 600 μm (No. 30
In the case of coal and coke, the methods used shall be those
U.S.A. Standard Sieve Series.) D4749 prescribed in Test Method D3172.
D121 − 15 (2024)
float/sink, n—a reference to the physical action that particles qualitative or quantitative corrections to be made to other
undergo when immersed in a liquid of a predetermined geophysical logs which are affected by borehole size (espe-
specific gravity. cially density).
DISCUSSION—A series of float/sink tests is considered as being
density log (gamma-gamma log), n—measures electron den-
synonymous with a washability analysis. A float fraction or float
sity within lithologic units which is related to their bulk
material is the material or the specific gravity fraction that floats in a
density. The wireline tool records the intensity of gamma
certain solution of specific gravity liquids. A sink fraction or sink
radiation (in counts per second) from a nuclear source within
material is the material or the specific gravity fraction that sinks in a
the tool after it has been attenuated and backscattered by
certain solution of specific gravity liquids. D4371
lithologies within the borehole. Due to the distinctly low
floor, n—the rock material immediately underlying a coal bed.
density of coals, the density log is essential in coal exploration
for identifying coal seams and coal-seam partings. The bias/
flotation cell, n—the vessel or compartment in which the
resolution of density logs can be affected by source-detector
flotation test is performed. D5114
spacing (closer spacing increases resolution), borehole size,
and irregularities (see caves or washouts), and the presence of
fluid temperature (FT), n—in reference to the fusibility of
casing and logging speed.
coal and coke ash according to Test Method D1857, the
temperature at which the fused mass has spread out in a
natural gamma-ray log, n—a record of the natural radioac-
nearly flat layer with a maximum height of 1.6 mm ( ⁄16 in.).
tivity of the lithologies encountered in the borehole environ-
D1857
ment. During recording of geophysical logs, the amount of
natural radiation is recorded and presented in either counts per
fluidity, maximum, n—as used in this test method, the
second (CPS) or American Petroleum Institute (API) units.
measured maximum stirrer rotation rate, in dial divisions per
Unlike many other log types, a representative natural gamma
minute. D2639
log can be obtained where borehole or fluid conditions, or both,
are not optimal or where casing is present. The natural gamma
free impurity, n—the impurities in a coal that exist as
log is most often used in the coal environment for identifying
individual discrete particles that are not a structural part of
clastic lithologies and differentiating coal seams and coal-seam
the coal and that can be separated from it by coal preparation
partings.
methods.
resistivity log, n—a measure of the voltage differential of
free moisture—synonym for surface moisture.
strata along the walls of a borehole when electrical current is
passed through the strata. The resistivity log requires a fluid-
froth, n—a collection of bubbles and particles on the surface of
filled hole to provide a conductive medium constantly between
a pulp in a froth flotation cell. D5114
electrodes on the tool. The spacing between the electrodes
froth flotation, n—a process for cleaning fine coal in which
determines the precision of the bed boundary relationships in
hydrophobic particles, generally coal, attach to air bubbles in
much the same manner as with the density log. The resistivity
a water medium and rise to the surface to form a froth. The
log is useful primarily in conjunction with other log types. The
hydrophilic particles, generally the ash-forming matter, re- logs are affected by casing, logging speed, electrode spacing,
main in the water phase. D5114
formation porosity, and resistivity changes in the borehole
fluid. D5192
frother, n—a reagent used in froth flotation to control the size
grade/recovery, n—the relationship between quality and quan-
and stability of the air bubbles, principally by reducing the
tity of the clean coal product. The quality can be defined in
surface tension of water. D5114
terms of ash, sulfur, or Btu content. The quantity can be
fusain—See fusain under coal.
designated as yield or heating value recovery (Btu or
fusinite—See fusinite under maceral.
combustibles). D5114
funginite, n—See funginite under maceral.
green coke, n—as used in Test Method D5061, carbonaceous
geophysical log, n—a graphic record of the measured or
binder or filler phase material that has exceeded the tem-
computed physical characteristics of the rock section en-
perature of thermoplasticity, but has not obtained the tem-
countered in a borehole, plotted as a continuous function of
perature of metallurgical coke.
depth. Measurements are made by a sonde which contains
DISCUSSION—Green coke is recognized on the basis of relative
the detectors, as it is withdrawn from the borehole by a wire
reflectance in comparison to fully carbonized coke. Green coke exhibits
line. Several measurements are usually made
varying degrees of lower reflectance than fully carbonized coke.
simultaneously, and the resulting curves are displayed side
D5061
by side on the common depth scale. A common suite of logs
gross calorific value (gross heat of combustion at constant
used in coal exploration include caliper, density (gamma-
volume), Q (gross) , n—the heat produced by combustion of
v
gamma), natural gamma, and resistivity.
unit quantity of a solid or liquid fuel when burned at constant
caliper log, n—a continuous mechanical measurement of the
volume in an oxygen bomb calorimeter under specified
diameter and thus the rugosity of the borehole. The tool
conditions, with the resulting water condensed to a liquid.
identifies zones where swelling or cavings (washouts) have
DISCUSSION—The conditions are initial oxygen pressure of 2 and 4
occurred during drilling. The tool’s value is in allowing MPa (20 to 40 atm), initial and final temperatures between 20 and 35 °C
D121 − 15 (2024)
(68 to 95 °F), products in the form of ash, water (aq), and gaseous
the same in all directions when viewed with an optical
carbon dioxide, sulfur dioxide, and nitrogen.
microscope having mutually exclusive polarized light, for
This definition is not applied to gaseous fuels and applies to a volatile
example, crossed nicols. D5061
liquid fuel only if it is suitably contained during the measurement so
that the vapor does not mix with the combustion oxygen before
laboratory sample—See laboratory sample under sample.
combustion.
lenticular anisotropic phase, n—as used in Test Method
The gross calorific value is closely related to the internal energy of
D5061, a group of binder-phase anisotropic carbon textures
combustion for the same reaction at constant standard temperature and
pressure, ΔU (at t ). It is of opposite sign and differs by a small distinguished by their lens-shaped domains (that is, length
°C °C
amount due to energy effects resulting from compression, temperature
(L) to width (W) ratio of 2W < L < 4W) and subdivided based
differences from t, and solution effects that vary with combustion
on domain widths as fine lenticular (1.0 to 3.0 μm), medium
conditions. Because of the variation of conditions allowed in the
lenticular (3.0 to 8.0 μm), and coarse lenticular (8.0 to
discussion above, the above definition does not lead to a unique value
12.0 μm) size categories. D5061
for any given fuel. However, the specified conditions limit the possible
values to a narrow range for which approximate limits can be calculated
lignite A—See lignite A under rank.
for a given fuel.
lignite B—See lignite B under rank.
gross sample—See gross sample under sample.
lignitic class—See lignitic class under rank.
heat capacity, n—Synonym for energy equivalent.
liptinite—See liptinite under macerals.
hemispherical temperature (HT), n—in reference to the
lithotype, n—(1) Rock form defined on the basis of certain
fusibility of coal and coke ash according to Test Method
selected physical characteristics. (2) One of the four macro-
D1857, the temperature at which the cone has fused down to
scopically recognized constituents of banded coal: vitrain,
a hemispherical lump at which point the height is one half
clarain, durain and fusain.
the width of the base. D1857
lithology—(1) Physical character or a rock, generally as
high volatile A bituminous coal—See high volatile A bitumi-
determined megascopically or with the aid of a low power
nous coal under rank.
magnifier. (2) The macroscopic study and description of
high volatile B bituminous coal—See high volatile B bitumi-
rocks. D5192
nous coal under rank.
lot, n—a discrete quantity of coal for which the overall quality
high volatile C bituminous coal—See high volatile C bitumi-
to a particular precision needs to be determined.
nous coal under rank.
impure coal—See impure coal under coal.
low volatile bituminous coal—See low volatile bituminous
incipient anisotropic phase, n—as used in Test Method
coal under rank.
D5061, a binder-phase carbon texture having a domain size
maceral, n—an organic substance in coal that is distinguished
(less than 0.5 μm) that is near the measuring resolution of the
and classified on the basis of its optical microscopic prop-
light microscope. D5061
erties.
increment, n—a small portion of a lot collected by one
DISCUSSION—Macerals originate from plant tissues, secretions, and
operation of a sampling device and normally combined with
exudates that have been altered by geological processes and may
contain up to several weight percent of inorganic elements in micro-
other increments from the lot to make a gross sample.
scopically indistinguishable form.
D2234/D2234M
alginite, n—a liptinite maceral that is generally spherical or
inertinite—See inertinite under maceral.
ovoid, frequently having a crenulated border and somewhat
inertodetrinite—See inertodetrinite under maceral.
irregular reflectance and sometimes occurring in clusters re-
inherent ash, n—the residue remaining from the inherent
flecting an origin from Botryococcus algae.
impurities after ignition under conditions specified for the
DISCUSSION—Alginite often occurs as degraded fragments derived
ash determination.
from colonial or unicellular bodies.
inherent impurity, n—the inorganic material in coal that is
cutinite, n—a liptinite maceral in the form of a sheet
structurally part of the coal and cannot be separated from it
reflecting its origin from leaf- or twig-covering plant cuticle,
by coal preparation methods.
frequently exhibiting reticulation in planar section and a
serrated edge in cross section.
inherent moisture—See inherent moisture under moisture.
initial deformation temperature (IT), n—in reference to the
exinite—Deprecated term. Use preferred term liptinite;
fusibility of coal and coke ash according to Test Method
sometimes has also been used as a synonym for sporinite.
D1857, the temperature at which the first rounding of the
fusinite, n—an inertinite maceral distinguished principally
apex of the cone occurs. Shrinkage or warping of the cone is
by the preservation of some feature(s) of the plant cell wall
ignored if the tip remains sharp.
structure, and with a particle size greater than 50 μm except
isoperibol, adj—a term used in combustion calorimetry mean-
when it occurs as a fragment within the binder matrix; see also
ing constant temperature jacket (environment).
semifusinite.
isotropic phase, n—as used in Test Method D5061, a binder- funginite, n—an inertinite maceral occurring as round or
phase carbon texture that exhibits optical properties that are ovoid bodies, frequently containing voids, reflecting an origin
D121 − 15 (2024)
ners place the division at Ro = 2.0 %; hence, semifusinite is somewhat
from fungal sclerotia; also occurs (especially in lower rank
vaguely defined as “fusinite with low reflectance.”
coals) as interlaced, stringy materials derived from fungal
hyphae. sporinite, n—a liptinite maceral exhibiting various lenticular,
oval, or round forms that reflect the cross-sectioning of a
inertinite, n—macerals that exhibit higher reflectance than
flattened, hollow, ovoid body; sometimes exhibits rod-like
other organic substances in the coal.
projections that are small relative to the size of the total body.
DISCUSSION—In any coal ranked lower than anthracitic, inertinite
DISCUSSION—Sporinite originated as a lipid substance that covered,
reflectance commonly spans the range from only slightly higher than
as a skin, ovoid spore or pollen grains which commonly ranged from
associated vitrinite to very high reflectance (often as high as Ro > 6 %).
around ten to several hundred micrometres in diameter. Sporinite often
In anthracitic rank coals, inertinite reflectance may be lower than that
occurs as fragments derived from these initially ovoid bodies.
of vitrinite, and is then recognized by its morphology and form of
anisotropy. Highly reflecting inertinite commonly exhibits relief on
vitrinite, n—the predominant maceral in most coals of
polished surface. Its name derives from the fact that most varieties
intermediate reflectance occurring as substantial volumes of
behave inertly in the thermoplastic deformation during the coking
more or less uniformly reflecting material or as a matrix
process (except in its lowest reflecting manifestation). The volatile
enclosing particles of other macerals and mineral matter or as
matter yield of inertinite is lower than that of other macerals in the same
particles or bands intermixed with other maceral fragments.
coal.
DISCUSSION—Because most vitrinite is derived from the cellular,
inertodetrinite, n—an inertinite maceral occurring as
structural tissues of plants, it may exhibit relict cell structure. The
individual, angular, clastic fragments incorporated within the
reflectance of vitrinite is related to the rank of the coal in which it is
matrix of other macerals (commonly vitrinite) or minerals, and
found. Reflectance increases (from around Ro = 0.3 % in lignitic coals)
in the size range from 2 to 50 μm.
in parallel with the increase in fixed carbon yield associated with
increasing rank. Because many of the properties of typical coals reflect
liptinite, n—macerals that exhibit lower reflectance than
the properties of the dominating vitrinite, it is common practice to
other organic substances in a coal, appearing black to dark gray
estimate coal properties and process behaviors by measuring the
and that fluoresce under blue to ultraviolet light in coals ranked
reflectance of a representative sampling of vitrinite in the specimen
high volatile bituminous and lower.
according to procedures described in Test Method D2798.
DISCUSSION—The fluorescence of liptinite distinguishes fine-grained
Pseudovitrinite, a certain variety of vitrinite, is differentiated by some
liptinite from similar sized, low reflectance, nonfluorescing clay min-
practitioners. It exhibits slightly higher reflectance than most of the
erals. Liptinite is derived principally from lipid substances forming
vitrinite in the coal and is commonly slitted, with indistinct remnant
skins (exines) and resinous secretions or exudates of plants. Liptinite is
cell structure and angular or jagged edges. Pseudov
...