2. Basic components
Cells and cell residues. Fragment of less than 5 or 10 connected cells.
Amorphous organic fine material. It can be two types:
Uniform material without any residues of coarse fragments being
Polymorphic. Residues of coarse fragments can be distinguished (>5%).
Punctuations. Very small dark points (approximately 1 mm).
Organic pigment. The mineral material is stained by the organic material.
There is a description of: size, shape, colour, transparency, birefringence, degree of alteration, etc.