calcite - teaching hand/display specimen of massive naturally-brown calcite forming a layer cake of

forming a layer cake of silty sediment and peat

Plate 17 shows butterflies of the genera  Papilio and Parnassius

Aragonite-based scleractinian corals replaced the calcite-based tabulate reef building corals during the Permo-Triassic extinction event roughly 252 million years ago

The angular nature of these grains shows that transport was short

endorheic lakes in the Basin and Range Province

calcite - teaching hand/display specimen of massive naturally-brown calcite forming a layer cake ofThis calcite is recrystallized from a limestone in contact with a granitic intrusion. The brown color is unusual and is derived from iron in the limestone that was released by the metamorphism. It effervesces in dilute hydrochloric acid (muriatic acid is the same) as does all calcite. The crystals of this calcite are interlocking, so it does not cleave into large rhombs, though individual specimens show many cleavage faces in several directions. The