Natural stone - Terminology

This European Standard defines the recommended terminology covering scientific and technical terms, test methods, products, and the classification of Natural Stones. This standard does not cover roofing slate, for roofing slate see EN 12326-1 and EN 12326-2.

Naturstein - Terminologie

Diese Europäische Norm definiert die empfohlene Terminologie für wissenschaftliche und technische Begriffe, Prüfverfahren, Produkte und die Klassifizierung von Naturstein. Dachschiefer werden durch diese Norm nicht abgedeckt; für Dachschiefer siehe EN 12326-1 und EN 12326-2.

Pierre naturelle - Terminologie

La présente Norme européenne définit une terminologie recommandée des termes scientifiques et techniques, des méthodes d’essai et des produits ainsi qu’une classification des pierres naturelles. La présente norme ne couvre pas l'ardoise de toiture ; pour celle-ci, voir les EN 12326-1 et EN 12326-2.

Naravni kamen - Terminologija

Ta evropski standard opredeljuje priporočeno terminologijo, ki zajema znanstvene in tehnične izraze, preskusne metode, izdelke ter klasifikacijo naravnih kamnov. Ta standard ne zajema skrilavca za strehe, za slednjega glej standarda EN 12326-1 in EN 12326-2.

General Information

Status
Published
Publication Date
16-Jul-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
10-Jul-2019
Due Date
14-Sep-2019
Completion Date
17-Jul-2019

RELATIONS

Effective Date
01-Sep-2019

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SLOVENSKI STANDARD
SIST EN 12670:2019
01-september-2019
Nadomešča:
SIST EN 12670:2002
Naravni kamen - Terminologija
Natural stone - Terminology
Naturstein - Terminologie
Pierre naturelle - Terminologie
Ta slovenski standard je istoveten z: EN 12670:2019
ICS:
01.040.73 Rudarstvo in rudnine Mining and minerals
(Slovarji) (Vocabularies)
01.040.91 Gradbeni materiali in gradnja Construction materials and
(Slovarji) building (Vocabularies)
73.020 Rudarstvo in kamnolomsko Mining and quarrying
izkopavanje
91.100.15 Mineralni materiali in izdelki Mineral materials and
products
SIST EN 12670:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 12670:2019
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SIST EN 12670:2019
EN 12670
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2019
EUROPÄISCHE NORM
ICS 01.040.91; 91.100.15 Supersedes EN 12670:2001
English Version
Natural stone - Terminology
Pierre naturelle - Terminologie Naturstein - Terminologie
This European Standard was approved by CEN on 15 April 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, North

Macedonia, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12670:2019 E

worldwide for CEN national Members.
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SIST EN 12670:2019
EN 12670:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

3.1 Geological terms .............................................................................................................................................. 5

3.2 Quarrying terms ........................................................................................................................................... 58

3.3 Processing terms .......................................................................................................................................... 64

3.4 Products and installation terms ............................................................................................................. 73

4 Scientific classifications ............................................................................................................................. 79

4.1 Geological time scale (informative) ...................................................................................................... 79

4.2 Scientific classification charts ................................................................................................................. 80

4.2.1 Igneous Rocks Classification Charts ...................................................................................................... 80

4.2.2 Sedimentary Rocks Classification Charts ............................................................................................ 88

4.2.3 Most common specific names of metamorphic rocks (list modified after Fettes and

Desmons, 2007) ............................................................................................................................................ 94

Annex A (informative) Examples of petrographical families/groups used in building ..................... 96

Annex B (informative) Alphabetical index ....................................................................................................... 100

Bibliography ............................................................................................................................................................... 112

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SIST EN 12670:2019
EN 12670:2019 (E)
European foreword

This document (EN 12670:2019) has been prepared by Technical Committee CEN/TC 246 “Natural

stones”, the secretariat of which is held by UNI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by December 2019, and conflicting national standards

shall be withdrawn at the latest by December 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 12670:2001.
In comparison with the precious edition, the following changes have been made:

— the changes concern essentially the proper scientific definitions, terminology, and diagrams.

This document is one of a series of standards for natural stone products including denomination, test

methods and product standards.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
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SIST EN 12670:2019
EN 12670:2019 (E)
Introduction

The term Natural Stone groups several rock types with marked geological differences. The extraction,

elaboration and commerce of Natural Stone have set a very particular vocabulary. Many of these terms

have been taken from the popular or quarrymen language, which sometimes is far from scientific

definitions. This document establishes the terminological bases for geological and petrologic definitions

of Natural Stone and its classification. References to definitions of natural stone products, defined in

other European Standards, are provided when necessary. It also incorporates most of the popular or

commercial terminology.

The terminology covers the fields of geology, mining, processing, marketing and products of Natural

Stone. The included scientific classifications allow setting the scientific name of the stone varieties. If

the stone variety is not included in this document, the rock should be classified using its three main

mineralogical components.
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EN 12670:2019 (E)
1 Scope

This document defines the recommended terminology covering scientific and technical terms, test

methods, products, and the classification of Natural Stones. This document does not cover roofing slate,

for roofing slate see EN 12326-1 and EN 12326-2.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 12326-1, Slate and stone for discontinuous roofing and external cladding - Part 1: Specifications for

slate and carbonate slate

EN 12326-2, Slate and stone for discontinuous roofing and external cladding - Part 2: Methods of test for

slate and carbonate slate
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Geological terms
3.1.1
accessory minerals

rock forming minerals that occur in such small amounts that they are not relevant in the classification

or nomenclature of the rock
3.1.2
acid rock
igneous rock that contains more than 66 % vol. of silica
3.1.3
actinolite
Ca-Mg-Fe-amphibole (see amphibole formula)
3.1.4
agate
distinctly banded variety of chalcedony
3.1.5
age
fourth order geological time unit
Note 1 to entry: See Table 2.
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3.1.6
agglomerate
pyroclastic rock in which bombs (with diameters greater than 64 mm) > 75 % vol.
3.1.7
agglutinate

welded splatter, commonly of basaltic composition, deposited ballistically in strombolian or fire

fountain volcanic eruptions
3.1.8
alabaster

fine grained, compact variety of gypsum, usually white or pale coloured and translucent

3.1.9
albite
sodium plagioclase, formula Na(AlSi O ) (see plagioclase)
3 8
3.1.10
alkali feldspar

alkali rich feldspars microcline, orthoclase, sanidine, albite, with less than 5 % vol. anorthite

Note 1 to entry: See feldspar and plagioclase.
3.1.11
allochems

coarser framework grains in most mechanically deposited limestones in the basin of sedimentation

Note 1 to entry: Allochems include: intraclasts, ooids, skeletal particles, pellets (including peloids).

3.1.12
allotriomorphic
anhedral
xenomorphic

mineral which shows in thin sections no characteristic or rational faces, suggested by its crystalline

structure
3.1.13
alteration

post-formational change of the mineralogical and or chemical composition of a rock brought about by

physical, chemical, or biological means, including actions of hydrothermal solutions and weathering

processes, excluding metasomatic and metamorphic changes
3.1.14
alumina
Al O
2 3
chemical compound used in fine polishing
3.1.15
amorphous
phase that does not have a crystalline structure
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3.1.16
amphibole

family of dark ferromagnesian silicate minerals, general formula A B (Si,Al) O (OH) , where A = Mg,

2-3 5 8 22 2
2+ 2+ 3+
Fe , Ca, Na; B = Mg, Fe , Fe , Al
3.1.17
amphibolite

gneissose or granofelsic metamorphic rock mainly consisting of green, brown, or black amphibole and

plagioclase

Note 1 to entry: A gneissose/granofelsic mesostructure is typical of true amphibolites, in contrast with

schistose, green amphibole-albite greenschists.
3.1.18
amygdaloidal

texture of volcanic rocks where almond-shaped vesicles are, fully or partially, filled with secondary

minerals
3.1.19
analcime
mineral, Na(AlSi O )H O of the zeolite group
2 6 2
Note 1 to entry: See zeolite, secondary minerals.
3.1.20
andalusite
mineral, Al SiO polymorphous with sillimanite and kyanite
2 5
3.1.21
andesite

volcanic rock of intermediate composition mainly composed of plagioclase (oligoclase - andesine) and

one or more of the mafic minerals amphibole, pyroxene, and biotite
Note 1 to entry: See 4.2.1.5
3.1.22
anhedral
(see allotriomorphic, 3.1.12)
3.1.23
anhydrite
mineral with CaSO formula
3.1.24
anisotropy

vectorial behaviour of physical and mechanical properties in minerals and rocks, i.e. hardness in

kyanite, thermal expansion in calcite, flexural resistance in slate
3.1.25
ankerite
mineral of dolomite group with calcium and iron
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3.1.26
anorthite
calcic plagioclase, Ca (Al Si O )
2 2 8
Note 1 to entry: See plagioclase.
3.1.27
anorthoclase
sodium-rich mineral of the alkali feldspar group, formula (Na,K)AlSi O
3 8

Note 1 to entry: Its composition, in terms of the mole fraction of the orthoclase component (or) and the albite

component (ab) is or ab to or ab (see feldspar, microcline, plagioclase, orthoclase).

40 60 10 90
3.1.28
anorthosite

plutonic rock mainly composed of anorthite – rich plagioclase and little or no mafic minerals

Note 1 to entry: See 4.2.1.2.
3.1.29
antiperthite
perthitic intergrowth of plagioclase host and subsidiary K-rich feldspar
3.1.30
apatite
group of minerals, of which the formula is Ca (PO ,CO ) (F,OH,Cl)
5 4 3 3
3.1.31
aphanitic

of or relating to an igneous rock in which the crystals are so fine that individual minerals cannot be

distinguished with the naked eye

Note 1 to entry: Aphanitic rocks are extrusive rocks that cooled so quickly that crystal growth was inhibited.

3.1.32
aplite

fine grained igneous rock of granitic composition with allotriomorphic texture and, commonly,

leucogranitic composition
3.1.33
aragonite
mineral, polymorphous with calcite, of which the formula is CaCO
3.1.34
Archaean

the older eon of the Precambrian ranging from the formation of the Earth at ~4 000 Ma to 2 500 Ma

Note 1 to entry: See Table 1.
3.1.35
arenite

loose soil or consolidated sedimentary rock, mainly composed of sand size detrital lithic fragments or

mineral grains (between 1/16 mm and 2 mm)

Note 1 to entry: Usually the term is used with a prefix that refers to its composition or genesis, e.g.

quartzarenite (see 4.2.2.5).
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3.1.36
argillite

layered or not-layered consolidated sedimentary rock mainly composed of detrital clay size particles or

clay minerals
3.1.37
arkose

sedimentary detrital rock with less than 75 % vol. quartz and a high content of feldspar grains

Note 1 to entry: See 4.2.2.5.
3.1.38
arkosic wacke

sandstone comprising >5 % vol. of sand grade particles, with the feldspar content exceeding that of rock

fragments and >15 % vol. of mud matrix (material <30 µm in diameter)
3.1.39
ash
fine-grained volcanic material
3.1.40
augen fabric

fabric in some rocks, usually metamorphic, consisting of ellipsoidal or lens shaped porphyroblasts,

crystals, or fragments, rounded and enveloped by the foliation, resembling eyes (augen) in a cross

section
3.1.41
augen mylonite

mylonite containing distinctive large crystals or lithic fragments around which the foliated fine-grained

matrix is wrapped, often forming symmetric or asymmetric trails
3.1.42
augite
clinopyroxene
mineral of the pyroxene group (clinopyroxenes), the general formula of which is
2+ 3+

(Ca,Na)(Mg,Fe ,Al)(Si,Al) O with minor amounts of Na, Fe , Al, Ti admitted, the colour of which is dark

2 6

green to black, and which is an essential constituent in basic igneous rocks such as basalts and gabbros

3.1.43
bafflestone

autochthonous carbonate rock whose original components were bound organically during deposition,

the organisms forming baffles to trap finer matrix material
3.1.44
banded

rock having alternating nearly parallel layers that differ in colour, fabric or mineral composition, and

because of that it shows alternating bands in a cross section
3.1.45
basalt

volcanic rock consisting essentially of plagioclase (labradorite-bytownite) and pyroxene with variable

amount of phenocrysts set in a fine-grained matrix

Note 1 to entry: Commercially natural stone as per the scientific definition of basalt and other rocks such as,

picrites, diabases, dolerites and microgabbros.
Note 2 to entry: See 4.2.1.5.
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3.1.46
basanite

silica-undersaturated alkali olivine basalt containing olivine, clinopyroxene and plagioclase feldspar

with >10 % vol. feldspathoids in the form of nepheline or leucite, which is found in association with

other alkaline igneous rocks
3.1.47
basic

Mg,- Fe- and Ca-rich igneous rock with more than 45 % vol. and less than 52 % vol. of silica

3.1.48
bed of blocks
unweathered rock beneath unconsolidated material formed by blocks
3.1.49
bedding plane

a) planar or nearly planar surface that visibly separates the individual beds, layers or strata, in

sedimentary rocks;
b) any surface, even when conspicuously bent or deformed by folding
3.1.50
benmoreite
alkali lava intermediate in composition between mugearite and trachyte
3.1.51
bindstone

autochthonous carbonate rock whose original components were bound organically during deposition,

with the organisms binding finer matrix material together
3.1.52
bioclastic rock

sedimentary rock consisting of fragments and broken remains of organisms; e.g. limestone composed of

shell fragments
3.1.53
biolithite
limestone essentially constituted of reef structures, animal or plant
3.1.54
biotite
2+ 3+

mafic rock forming mineral of the mica group with general formula K(Mg,Fe ) (Al,Fe ) Si O (OH)

3 3 10 2
3.1.55
black granite
commercial term for black or dark coloured plutonic rocks
Note 1 to entry: See e.g. gabbro, diabase, basalt.
3.1.56
blasto-

prefix used to describe the metamorphic rock fabrics denoting the presence of primary crystals or pre-

existing fabric modified by metamorphism, but still recognized; e.g. blastogranular, blastomylonitic,

blastopsephitic
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3.1.57
blastomylonite

mylonite which displays a significant degree of grain growth related to or following deformation

3.1.58
block
angular fragment of rock with a diameter >256 mm
3.1.59
blue schist
schist whose bluish colour is due to the presence of sodic amphibole
3.1.60
bomb

mass of liquid lava thrown through the air which rotates and takes on a characteristic shape and

structure
3.1.61
boundstone
limestone, in which the grain were bound by an organism or organisms
3.1.62
breccia

a) coarse grained clastic sedimentary rock composed by angular rock fragments held together by a

mineral cement or in a fine grained matrix;

b) clastic rock consisting of highly angular gravel-size fragments, of sedimentary, tectonic or volcanic

origin
3.1.63
calc silicate marble
marble with calcium and silicate minerals
Note 1 to entry: See marble, ophicalcite.
3.1.64
calcarenite

limestone consisting predominantly of recycled detrital calcite grains of sand size (1/16 mm – 2 mm)

3.1.65
calcareous
containing calcium carbonate
3.1.66
calcilutite

limestone consisting predominantly of detrital calcite grains or fragments of silt or clay size (<1/16

mm)
3.1.67
calciphyre

metacarbonate rock containing a conspicuous amount of calcium- and/or magnesium-silicate minerals

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3.1.68
calcirudite

limestone consisting predominantly of detrital calcite grains or fragments larger than sand size

Note 1 to entry: See rudite.
3.1.69
calcisiltite

limestone consisting predominantly of detrital calcite grains or fragments of silt size

3.1.70
calcite
mineral, the formula of which is CaCO ; trimorphous with aragonite and vaterite
Note 1 to entry: Very common in some sedimentary and metamorphic rocks.
3.1.71
calcitic dolomite
carbonate rock which 50 % vol. to 89 % vol. of the mineral dolomite
Note 1 to entry: See also 4.2.2.11.
3.1.72
calcitic marble
marble containing more than 50 % vol. of calcite
3.1.73
calc-schist
carbonate silicate-schist

metamorphosed argillaceous limestone containing calcite as a substantial component and with a

schistose structure produced by parallelism of platy minerals

Note 1 to entry: The term carbonate-silicate schist should be used when the non-carbonate mineral content is

>50 % vol. See schist, 4.2.3.
3.1.74
Cambrian
oldest system and period into which the Palaeozoic is divided
Note 1 to entry: See Table 1.
3.1.75
carbonate

mineral containing CO ; calcite, dolomite, magnesite, and siderite, etc. which are frequent rock forming

carbonate minerals
3.1.76
carbonate rock

rock consisting chiefly of carbonate minerals, especially a sedimentary rock; limestone, dolomite, and

carbonatite are examples of carbonate rocks
Note 1 to entry: See 4.2.2.8, 4.2.2.9, 4.2.2.10 and 4.2.2.11.
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3.1.77
carbonate-silicate rock

metamorphic rock mainly composed of silicate minerals (including calcium-silicate minerals) and

containing between 5 % vol. vol and 50 % vol. vol of carbonate minerals
3.1.78
Carboniferous
period and system of the Palaeozoic
Note 1 to entry: See Table 1.
3.1.79
cataclasite

fault rock which is cohesive with a poorly developed or absent schistosity, or which is incohesive,

characterised by generally angular porphyroclasts and lithic fragments in a finer-grained matrix of

similar composition

Note 1 to entry: Generally, no preferred orientation of grains of individual fragments is present as a result of the

deformation, but fractures may have a preferred orientation. A foliation is not generated unless the fragments are

drawn out or new minerals grow during the deformation. Plastic deformation may be present but is always

subordinate to some combination of fracturing, rotation and frictional sliding of particles. Cataclasite may be

subdivided according to the relative proportion of finer-grained matrix into protocataclasite, mesocataclasite and

ultracataclasite
3.1.80
cataclastic

pertaining to the structure and texture produced in a rock by severe mechanical stress during dynamic

metamorphism; bending, breaking, and fragmentation of the mineral grains are characteristic features;

also said of the rocks exhibiting such structure
Note 1 to entry: See breccia.
3.1.81
cement

mineral material, usually chemically precipitated during the rock compaction that occurs in the

interstitial spaces among the individual grains of a sedimentary rock, thereby binding the grains

together as a rigid mass; silica, carbonates and iron oxides are common cements
3.1.82
Cenozoic
youngest era of geologic time
Note 1 to entry: See Table 1.
3.1.83
chalcedony

group name for the compact varieties of silica composed of minute crystals of quartz with sub

microscopic pores
3.1.84
chalcopyrite
sulphide mineral, the formula of which is CuFeS2
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3.1.85
chalk

soft fine grained limestone, usually white consisting mostly of calcitic remains from microorganisms,

and minor silt and clay
3.1.86
charnockite
orthopyroxene-bearing rock of granitoid composition
3.1.87
chert

fine-grained, hard, compact and dense sedimentary rock, consisting dominantly of the SiO minerals

quartz, chalcedony and opal. cryptocrystalline and/or amorphous silica
Note 1 to entry: Flint is a variety of chert.
3.1.88
chlorite Group
2+ 3+

group of phyllosilicates, some of them of green colour, with general formula (Mg, Fe , Fe )

AlSi O (OH)
3 10 8
3.1.89
chloritoid
micaceous mineral, the formula of which is Fe Al Si O (OH)
2 4 2 10 4
3.1.90
chromite
mineral, the formula of which is (Fe,Mg)(Cr,Al) O
2 4
3.1.91
chronostratigraphic unit
stage or zone which, independent of facies, represents a layer of specific age
3.1.92
cipollino marble

impure marble with band coloured structure, consisting in layers of calcite or dolomite grains mixed

with variable quantities of silicate minerals
3.1.93
clast
mineral or rock fragment composing clastic sedimentary rocks
3.1.94
cisuralian
oldest epoch of the Permian
Note 1 to entry: See Table 1.
3.1.95
clastic

pertaining to a rock or sediment composed principally of broken fragments that are derived from pre-

existing minerals, rocks or organic structures and that have been transported some distance from its

original place
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3.1.96
clay minerals

group of minerals, essentially hydrous silicates of aluminium with a layered crystalline structure; iron,

magnesium, potassium, and other cations are also present in their formula; the most common of which

belong to illite, montmorillonite, and kaolinite mineral subgroups
3.1.97
clay slate
shale

weakly metamorphosed clay stone with intermediate character between a clay stone and a true slate

3.1.98
clay

loose, extremely fine grained sediment or soft rock composed of particles with diameters less than

0,002 mm, mainly of clay minerals and other minerals, especially quartz, feldspars, and carbonates

3.1.99
clay stone
rock with more than 67 % vol. clay sized minerals
3.1.100
cleavage

a) property of a rock to split along closely spaced planar surfaces (see slaty cleavage, crenulation

cleavage, schistosity, and rough cleavage);

b) splitting of a mineral along its crystallographic planes, thus reflecting crystal structure

3.1.101
clinopyroxene
monoclinic pyroxene exhibiting non-parallel extinction
3.1.102
columnar

structure of some volcanic rocks, such as basalt, consisting of parallel, prismatic columns, polygonal in

cross section, nearly perpendicular to the top and the bottom of the flow unit
3.1.103
comb layering

fabric of igneous rocks consisting of bands of elongated crystals with nearly vertical mineral-elongation

relative to the border of the bands
3.1.104
concretion

collective term applied loosely to various primary and secondary segregations of diverse origin,

including irregular nodules, spherulites, crystalline aggregates, geodes, septarias and related bodies

3.1.105
conglomerate

coarse grained sedimentary rock composed of rounded to sub angular fragments (pebbles, cobbles,

boulders), set in a fine grained matrix of sand or clay, and commonly cemented
3.1.106
consertal
fabric of rocks showing toothed border lines between adjoining crystals
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3.1.107
contact (between grains)

mode of relation between grains of rock-forming minerals; i.e. by points, by lines, within the matrix

3.1.108
coral rock
coral reef limestone
3.1.109
cordierite

silicate mineral, common in some metamorphic and rare in magmatic rocks, the formula of which is

(Mg,Fe) Al Si O
2 4 5 18
3.1.110
corona

fabric of igneous or metamorphic rocks where minerals are surrounded by a seam of one or more other

minerals

Note 1 to entry: Particular examples are the rapakivi fabric and kelyphitic rims.

3.1.111
Cretaceous
youngest of the periods/ and systems included in the Mesozoic era/erathem
Note 1 to entry: See Table 1.
3.1.112
cross bedding
cross stratification with thick individual beds
3.1.113
crossed twinning

lamellae of mineral twins after two laws making in thin sections a grid as seen in microcline

3.1.114
cryptocrystalline

composed of crystals so fine that they cannot be recognized even under polarizing microscope

3.1.115
crystal zoning

texture of igneous crystals with concentric layers made by inclusions or variations in chemical

composition e.g. in plagioclases
3.1.116
dacite

volcanic rock with quartz, plagioclase, alkali feldspar, and often mafic components

Note 1 to entry: See 4.2.1.5.
3.1.117
dark mineral
mafic mineral
Fe-Mg rock forming minerals, e.g. olivine, pyroxenes, amphiboles and biotite
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SIST EN 12670:2019
EN 12670:2019 (E)
3.1.118
decussate

metamorphic fabric of randomly oriented unequidimensional grains (e.g. pyroxenes, micas)

3.1.119
dedolomitization
partial or complete calcification of dolomite
3.1.120
deformation fabric
tectonic fabric

rock fabric resulting from deformation, as lineation, cleavages, schistosity, folds, preferred orientations

of crystals etc.
Note 1 to entry: See fabric.
3.1.121
devitrification

process of nucleation and growth of crystals in glasses at sub solidus temperatures

3.1.122
Devonian
system of the Palaeozoic Erathem above the Silurian and below the Carboniferous
Note 1 to entry: See Table 1.
3.1.123
diabase

medium grained rock of basaltic composition used in two ways: altered basaltic rocks (British) and

ophitic texture (French, German and American)
3.1.124
diagenesis

process of mineralogical changes in sediments after deposition which result in a consolidated rock

3.1.125
diamictite
terrigenous sedimentary rock with particle sizes
...

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