BIOCHEMICAL -  contain particles derived from some lifeform


The rock is composed of calcite - limestone
The rock reacts with dilute HCl to effervesce

Limes~44.jpg (10346 bytes) Limes~46.jpg (7615 bytes)


The rock is composed of carbon  - member of the coal series

peat


lignite


bituminous coal


anthracite coal

Coal.jpg (7315 bytes)