ISO 7404-1:2016

Methods for the petrographic analysis of coals - Part 1: Vocabulary

ISO 7404-1:2016 defines terms that are used in connection with both maceral and microlithotype analyses, and with the determination of the reflectance of vitrinite. It applies to the terms used in the examination of coal of all ranks. ISO 7404-1:2016 is not intended to be a comprehensive glossary of coal petrographic terminology, nor does it attempt to provide sufficient information to allow recognition of all the coal components described. Further information may be obtained from the relevant ICCP publications[3][4][5].

Méthodes d'analyse pétrographique des charbons — Partie 1: Vocabulaire

General Information

• Status: Published
• Publication Date: 22-Mar-2016
• ICS: 01.040.73 - Mining and minerals (Vocabularies)
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 5 - Methods of analysis
• Drafting Committee: ISO/TC 27/SC 5/WG 14 - Petrographic analysis of coals
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 27-Oct-2025
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 7404-1:2025 - Coal - Methods for petrographic analysis - Part 1: Vocabulary
• Effective Date: 27-May-2023
• Revises: ISO 7404-1:1994 - Methods for the petrographic analysis of bituminous coal and anthracite - Part 1: Vocabulary
• Effective Date: 18-Oct-2014

Overview

ISO 7404-1:2016 specifies the standardized vocabulary used in the petrographic analysis of coals. It defines terms applied to maceral and microlithotype analyses and to the determination of the reflectance of vitrinite. The standard applies to examinations of coal of all ranks and is intended to support consistent, comparable petrographic reporting rather than to serve as a comprehensive glossary. Where further detail is required, users are referred to ICCP publications and the other parts of ISO 7404.

Why this matters: consistent terminology improves communication between laboratories, geologists and technologists, and underpins reliable maceral analysis, vitrinite reflectance measurement and interpretation of coal behaviour.

Key Topics

• Scope and purpose: Vocabulary for maceral, microlithotype and vitrinite reflectance measurements applicable to coals of all ranks.
• Optical microscopy terms: Definitions include reflectance (measured under oil immersion), random and maximum reflectance, reflectance standards and zero standards, and parasitic reflection.
• Macerals: The three maceral groups are defined: vitrinite (huminite equivalent), liptinite, and inertinite, with subgroups and varieties referenced to the ICCP system.
• Microlithotypes: Defined as naturally occurring macerals or maceral associations (minimum layer width 50 μm). Classification rules require monomaceral, bimaceral or trimaceral categories where principal maceral groups constitute >=95% (mineral-free basis).
• Carbominerites and minerites: Collective terms for intergrowths of minerals and macerals; minerite is used when mineral content exceeds defined volumetric thresholds.

Applications

ISO 7404-1:2016 supports practical petrographic workflows and laboratory reporting:

• Standardizes terms used in maceral group composition and microlithotype analysis, aiding reproducibility.
• Supports interpretation of coal rank through vitrinite reflectance; vitrinite reflectance is cited as a key measure of coalification and rank.
• Enables consistent documentation for geological studies, coal quality assessment and technological testing (e.g., coking, combustion behaviour) when combined with procedural parts of ISO 7404.

Practical benefits include improved inter-laboratory comparison, clearer specification of analytical results in contracts, and a shared basis for research and regulatory reporting.

Related Standards

• ISO 7404 (other parts): Part 2 (sample preparation), Part 3 (maceral group composition), Part 4 (microlithotype, carbominerite and minerite composition), Part 5 (microscopic vitrinite reflectance determination).
• ICCP publications and classification systems referenced for detailed maceral and inertinite classifications.
• ISO 11760 (classification of coals) for complementary rank and classification context.

Note: ISO 7404-1:2016 defines terminology to be used alongside the analytical methods in the remaining parts of ISO 7404 and referenced ICCP literature. It does not provide exhaustive identification procedures for every coal component.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7404-1
Third edition
2016-04-01
Methods for the petrographic analysis
of coals —
Part 1:
Vocabulary
Méthodes d’analyse pétrographique des charbons —
Partie 1: Vocabulaire
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 1
2.1 General terms . 1
2.2 Optical microscopy terms . 2
2.3 Petrographic terms . 3
3 Classification of macerals, microlithotypes and carbominerites .4
3.1 Macerals . 4
3.2 Microlithotypes . 4
3.3 Carbominerites . 5
Bibliography . 6
Foreword
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The committee responsible for this document is ISO/TC 27, Solid mineral fuels, Subcommittee SC 5,
Methods of analysis.
This third edition cancels and replaces the second edition (ISO 7404-1:1994), which has been technically
revised.
ISO 7404 consists of the following parts, under the general title Methods for the petrographic analysis
of coals:
— Part 1: Vocabulary
— Part 2: Method of preparing coal samples
— Part 3: Method of determining maceral group composition
— Part 4: Method of determining microlithotype, carbominerite and minerite composition
— Part 5: Method of determining microscopically the reflectance of vitrinite
iv © ISO 2016 – All rights reserved

Introduction
Petrographic analyses have been recognized internationally as important in the context of the genesis,
vertical and lateral variation, continuity, metamorphism and usage of coal. The International Committee
for Coal and Organic Petrology (ICCP) has made recommendations concerning nomenclature and
[3][4][5]
analytical methods and has described in detail the characteristics of a wide range of coals . The
text of this part of ISO 7404 agrees substantially with the text of the relevant ICCP publications and
incorporates many useful comments made by members of the ICCP and by member bodies of ISO/TC 27,
Solid mineral fuels.
Petrographic analyses of a single coal provide information about the rank, the maceral and
microlithotype compositions and the distribution of minerals in the coal. The reflectance of vitrinite is
a useful measure of coal rank and the distribution of the reflectance of vitrinite in a coal blend, together
with a maceral group analysis, can provide information about important chemical and technological
properties of the blend.
ISO 7404 is concerned with the methods of petrographic analysis currently employed in characterizing
coal in the context of its technological and/or geological use. It establishes a system for petrographic
analysis and comprises five parts, as follows:
— Part 1: Vocabulary;
— Part 2: Method of preparing coal samples;
— Part 3: Method of determining maceral group composition;
— Part 4: Method of determining microlithotype, carbominerite and minerite composition;
— Part 5: Method of determining microscopically the reflectance of vitrinite.
The definitions given are intended for use solely in connection with the generally accepted international
methods of petrographic analysis of coal described in the other parts of ISO 7404.
The petrographic terms listed herein are those used by the ICCP and ISO. They do not include terms
such as, for example, pseudovitrinite, semi-vitrinite and semi-inertinite which refer to types of maceral
with particular properties, but which are sometimes difficult to define. Such terms may be considered
important for specific applications, but their wider use is not recommended.
INTERNATIONAL STANDARD ISO 7404-1:2016(E)
Methods for the petrographic analysis of coals —
Part 1:
Vocabulary
1 Scope
This part of ISO 7404 defines terms that are used in connection with both maceral and microlithotype
analyses, and with the determination of the reflectance of vitrinite. It applies to the terms used in the
examination of coal of all ranks.
This part of ISO 7404 is not intended to be a comprehensive glossary of coal petrographic terminology,
nor does it attempt to provide sufficient information to allow recognition of all the coal components
[3][4][5]
described. Further information may be obtained from the relevant ICCP publications .
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1 General terms
2.1.1
coal
combustible sedimentary rock formed from bio- and geochemically altered plant remains (peat)
consolidated under superimposed strata
Note 1 to entry: The characteristics of different coals are due to differences in source plant material, in the
conditions and the degree of change that the material has undergone in its geological history and in the range
of impurities present. Coal composition can be characterized microscopically by maceral and microlithotype
compositions.
2.1.2
coa
...