Most sources of crystals are in Brazil. The name quartz comes from the Greek word krustallos , meaning ice. Pearls Pearls are formed in shellfish oysters and mussels as a natural defense against an irritant such as a piece of sand or grit. Layers of aragonite are secreted around the irritant and gradually build up to form the solid pear. Light reflecting from these overlapping layers produces the iridescent luster.
Pearls are sensitive to acids, dryness and humidity.
This causes them to be less durable than other gems. Pearls were once thought to be the tears of the gods. Sodalite is found in all shades of blue and is the major component in the rock lapis lazuli. Unlike Lapis, Sodalite rarely contains brassy specks although it may contain white streaks of the mineral calcite. Turquoise - Turquoise occurs mainly as veins in sedimentary rocks such as shale.