||Plaster of paris. Gypsum is formed when seawater evaporates from the Earth’s surface.
||Limestone and most shells contain calcite.
||Fluorine from fluorite prevents tooth decay.
||Apatite is a mineral in vertebrate bones and teeth.
||Orthoclase is a feldspar, and in German, "feld" means "field".
||Quartz is the most common mineral in the Earth's crust.
||The November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8.
||Sapphire and ruby are varieties of corundum. Twice as hard as topaz.
||Used in jewelry and cutting tools. Four times as hard as corundum.