Geology Reference
In-Depth Information
Table 3.1.4a
Macropetrographic classification of brown coal lithotypes.
Categories
Lithotype classes
Lithotypes
Lithotype varieties (determined on dried material in laboratory)
Quality parameter
Structure: presence of xylite and/or
contamination by mineral matter
Texture: ratio between
groundmass and plant remains
Intensity and
hue of color
Evidence of
gelification
Additional
features
Inclusions
Macro-petrographic
description
(1) Pure coal, non-xylitic
Pure coal, xylitic
Fibrous xylite
Brittle xylite
(1) Unbanded coal
(1) Pale yellow (1) Gelified
groundmass (+, ++, +
++)
(1) Resin bodies
(+, ++, +++)
(a). Surface
texture
Extensive
cracking
Moderate
cracking
No cracking
(2)______
Tree stumps, tree trunks, etc.
Impure coal, non-xylitic
(2) Moderately banded coal
(2) Medium
light yellow
(2) Gelified tissues
(+, ++, +++)
(2) Cuticles
(+, ++, +++)
(b) Fracture
Even
imbricated
(3) Clayey coal, sandy coal, calcareous
coal, iron sulfides, etc.
(3) Banded coal
(3) Pale brown (3) Microgranular
humic gel particles
(+, ++, +++)
(3) Charcoal
(+, ++, +++)
(c) Size
degradation
Coarse
fragmentation
Fine
fragmentation
Crumbling
(4) Impure coal, xylitic
(4) Highly banded coal
(4) Medium
light brown
(5) Dark
brown
(6) Black
Source
: Lithotypes after Hagemann, 1980.
