A glassy, variously colored calcium phosphates: Apatite minerals are used as a source of phosphorous to be used in fertilizer, rarely as a gemstone, and as a mineral specimen.

1. A most common mineral and one of the most common minerals on the face of the Earth: Calcite minerals consist of about four percent by weight of the Earth's crust, and is formed in many different geological environments.

Calcite minerals are used in cements and mortars, in the production of lime, and limestone is used in the steel industry, in the glass industry, as ornamental stone, in chemical and optical uses, and as mineral specimens.
2. Etymology: from Latin calx +? -ite. The name from "chalix", the Greek word for lime.

Native aluminum oxide, the hardest naturally occurring mineral known apart from diamond (corundum rates 9 on the Mohs scale of hardness). The corundum mineral is the second hardest natural mineral known to science

A lack of cleavage also increases the durability of the corundum mineral . Its crystals are barrel-shaped prisms of the trigonal system.

Its two varieties are sure to be on any list of gemstones. The red variety of corundum is known as ruby and all the other colors of corundum are known as sapphire.

Besides being used as gemstones, corundum minerals are also utilized as an abrasive.