
Introduction
This Atlas of Coal Macerals presents the current classifications of the International Committee for Coal and Organic Petrology (ICCP) together with examples of coal macerals. Photomicrographs of macerals were taken on polished sections under a reflected light microscope (with oil objective) in white or fluorescent light.
Macerals are microscopically recognizable constituents of organic matter in coal. The term maceral was first used by Stopes in 1935 for a component of coal detected under a microscope. Over the years, the ICCP has established standard rules for maceral analysis, maceral definitions and classifications. This atlas uses the most current maceral classification as regulated by ICCP (ICCP System, 1994). Articles where these revised classifications are published (ICCP, 1998; 2001; Sykorova and others, 2005) are also included for reference. Permission to reprint these papers was granted by Elsevier.
LIGNITES and SUBBITUMINOUS COALS | |||||
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MACERAL GROUP | MACERAL SUBGROUP | MACERAL | MACERAL TYPE | MACERAL VARIETY | MACERAL EXAMPLE |
Huminite Derived from coalified woody tissue |
Telohuminite Comprises macerals with preserved intact botanical cell structures visible to various extents and isolated cells |
Textinite (Tx) Consists of ungelified cell walls either of isolated, but intact, individual cells or within tissues |
A (dark) and B (light) |
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Ulminite (U) Denotes the cell walls of more or less gelified tissues |
A (dark) and B (light) |
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Detrohuminite Consists of fine humic fragments ( |
Attrinite (A) Consists of a mixture of fine huminitic particles ( different shape and spongy to porous, ungelified amorphous huminitic substances |
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Densinite (D) Consists of fine huminitic particles ( |
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Gelohuminite Comprises macerals originating from amorphous humic matter |
Corpohuminite Consists of homogenous, discrete bodies of former humic cell fillings occurring in situ with textinite or ulminite or isolated within attrinite, densinite, or clay |
Phlobaphinite (Ph) Originates from tannin-rich cell excretions, deposited in cortical cells, in parenchyma-tous or medullary-ray cells and especially in cork tissues |
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Pseudophlobaphinite (Pd) Derives from colloidal humic solutions |
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Gelinite Appears under reflected light as homogenous structureless or porous substance of huminitic reflectance |
Levigelinite (L) Completely structureless, compact, and homogenous |
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Porigelinite (Pg) Spongy, porous, or microgranular texture |
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BITUMINOUS COALS AND ANTHRACITES | |||
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MACERAL GROUP | MACERAL SUBGROUP | MACERAL | MACERAL EXAMPLE |
VITRINITE
Derived from coalified woody tissue |
Telovitrinite Comprises vitrinites with preserved botanical cell structures which may or may not be visible |
Telinite (T) Consists of clearly recognizable cell walls of more or less intact plant tissue |
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Collotelinite (C) Consists of more or less homogenized vitrinite layers which may exhibit poorly defined structure |
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Detrovitrinite Consists of finely fragmented vitrinized plant remains occuring either isolated or cemented by amorphous vitrinic matter |
Vitrodetrinite (V) Occurs as discrete small vitrinitic fragments of varying shape that become discernible when surrounded by non-vitrinitic material |
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Collodetrinite (Cd) Occurs as a mottled vitrinitic ground mass binding other coal components |
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Gelovitrinite Consists of colloidal fillings of vitrinitic material in former voids |
Corpogelinite (Cg) Consists of homogenous and discrete bodies representing cell infillings |
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Gelinite (G) Consists of homogenous and structureless infillings of cracks and other voids |
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Liptinite Group | |||
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MACERAL | MACERAL EXAMPLE | ||
Sporinite (S) Derived from the waxy coating of fossil spores and pollen |
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Cutinite (Cu) Derived from the waxy outer coating of leaves, roots, and stems |
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Resinite (R) Derived from plant resins |
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Alginite (Ag) Derived from algae |
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Liptodetrinite (Ld) Occurs as discrete small liptinite fragments of varying shape |
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Suberinite (Sb) Cork cell walls |
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Chlorophyllinite Chlorophyl-derived material occurring in peat and very low maturity lignite. Not present above subbituminous coals. |
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Exsudatinite (E) Secondary maceral filling cracks and cell lumens, originating after oil generation |
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Fluorinite (Fl) Semi-globular occurrences of fluorescing droplets (oil precursors?) |
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Inertinite Group | |
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MACERAL | MACERAL EXAMPLE |
Micrinite (Mi) Occurs in very small rounded grains of high reflectance. It might originate from liptinites as a coalification product |
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Macrinite (Ma) Occurs either as an amorphous matrix or as discrete, structureless bodies of variable shapes; probably originates from flocculated humic matrix substances |
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Fusinite (F) Shows highly reflecting, well-preserved cellular structure; originates from ligno-cellulosic cell walls |
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Semifusinite (Sf) Shows intermediate reflectance and partially visible cellular structure; originates from the parenchymatous and xylem tissues of stems, herbaceous plants, and leaves, which are composed of cellulose and lignin |
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Secretinite (Sc) Composed of commonly round, and equant to elongate bodies without obvious plant structure; commonly considered to be an oxidation product of resin but it may originate from humic gels |
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Funginite (Fg) Consisting mainly of high reflecting single- or multi-celled fungal spores, sclerotia, hyphae and mycelia (stromata, mycorrhiza), and other fungal remains |
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Inertodetrinite (I) Occurs as discrete small inertinite fragments of varying shape |
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References
International Committee for Coal and Organic Petrology (ICCP), 1998.
The new vitrinite classification
(ICCP System 1994), reprinted from Fuel 77, p. 349-358, with permission from Elsevier.
International Committee for Coal and Organic Petrology (ICCP), 2001.
The new inertinite classification
(ICCP System 1994), reprinted from Fuel 80, p. 459-471, with permission from Elsevier.
Sykorova, I., Pickel, W., Christanis, K., Wolf, M., Taylor, G.H., Flores, D., 2005.
Classification of huminite
(ICCP System 1994) reprinted from International Journal of Coal Geology 62, p. 85-106, with permission from Elsevier.