Fossiliferous Limestone It forms from the accumulation of shells and skeleton remains of calcareous marine organisms and is an indicator for a warm, shallow marine deposition environment. Size: 25 cm Chalk Consolidated accumulation of minute calcite plates (coccoliths) shed from micro-organisms called coccolithophores. Size: 10 cm Coquina Incompletely consolidated rock composed dominantly of seashells and corals, forms in close association with coral reefs. Size: 10 cm Chert Cryptocrystalline form of silica formed by the decay of silica-rich organisms such as radiolarian Size: 15 cm Diatoms, Diatomite & Diatom Chert Consists of fossilized remains of diatoms, a hard shelled phytoplankton Size: 9 cm (Diatom Chert) Peat – Accumulation and cementation of plant remains Low energy and smoky when burned Size: 12 cm Lignite - Soft, brown coal-like material Moderate energy when burned Size: 10 cm Bituminous Coal – Carbonized plant remains soft, black high energy coal used in power generation Size: 10 cm Anthracite – Hard, black coal High energy coal, used in industry Size: 15 cm