calcite - teaching hand/display specimen of massive naturally-brown calcite The frosted quartz grains are

The frosted quartz grains are characteristic of the Navajo Sandstone - the quartz grains essentially sandblasted each other as they were transported by the wind and deposited in dunes

Plate 17 shows butterflies of the genera  Papilio and Parnassius

the partly dried perlite is heated to 1

with lifetimes on the order of milliseconds

calcite - teaching hand/display specimen of massive naturally-brown calcite The frosted quartz grains areThis 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