Just a few minerals make up most of the rocks we see, though: feldspars, amphiboles, quartz, olivine, garnet, micas, calcite, and pyroxenes. The possible combinations of these minerals are endless.

As the soft parts of the creature decayed, they created a local change in the geochemistry of the rock that permitted the crystallization of cement (usually calcite) between the grains of the sediment ...

The presence of calcite veins with alteration halos signifies pathways of hydrothermal fluid flow through the host limestone ...