Structural Characteristics and Physical Properties of Tectonically Deformed Coals

Table 1

The structural-genetic classification of TDCs.

Deformation series	Type of tectonically deformed coals	Texture and structure	Structural fracture and wrinkle	Breaking degree	Micro characteristics	Deformational mechanism and environment
Brittle deformation series	Cataclastic; structure coal	Band texture could be seen; layer structure was preserved	Multidirectional fracture cuts; no obvious displacement	More hardness; crumbing is difficult
	Mortar; structure coal	Little band texture was seen; lentoid structure was formed	Multidirectional fracture cuts; obvious displacement in the mortar	Broken into detritus from 1 to 5 cm; angular shape	Tensile fracture, shear fracture, and compressional fracture	Multi directional compression and extension; extension was the predominant role
	Granulitic; structure coal	Primary structure not present; disorder of players	Multi directional cross fracture; particles were rotated	Broken into detritus, 1 cm
	Mealy; structure coal	Primary structure not present; powdered particles formed	No obvious directions for the particles	Be pinched into powered particles		Strong compressional fracture zone or scaly structure coal be reconstructed later
	Schistose; structure coal	Band texture could be seen; layer structure was preserved	Single directional fracture; little displacement on the surface	Broken into detritus from 1 to 5 cm, shard shape		Single directional compression and extension or shearing strain environment
	Thin-layer; structure coal	Little band texture was seen; layer structure was not obvious	Single directional fracture; obvious displacement on the surface	Broken into detritus, 1 cm
Brittle-ductile series	Scaly; structure coal	Primary structure not present; scaly structure was formed	Multi directional cross-fracture; coal was cut and wrinkled; the particles could be rotated	Broken into detritus, 0.5 cm; shard shape	Shear fracture, cleavages	Strong shearing or cleaving strain environment
Ductile deformation series	Wrinkle; structure coal	Primary structure not present; wrinkle structure was formed	Coal was wrinkled	Broken into detritus, 0.5 cm, shard shape	Wrinkle, foliated coal, S-C structure, eyed structure, optical anisotropy structure and wavy extinction
	Mylonitic; structure coal	Primary structure not present; mylonitic structure was formed	The particles had directional arrangement; flow structure was formed	Was pinched into powered particles		Strong shearing or long and low stress deformation
	Ductile; structure coal	Primary structure not present; lump and lentoid structures were formed	No obvious physical deformation	More hardness; crumbing was difficult		Long and low stress creep; ductile flow at high temperatures