Calcite

Calcite is a carbonate mineral with the chemical formula CaCO₃. It is a common mineral found in sedimentary, metamorphic, and igneous rocks. Calcite is the primary mineral in limestone and marble, and it also occurs as a vein mineral in many deposits.

Physical Properties

• Color: Calcite can be colorless, white, yellow, orange, red, pink, blue, green, brown, or black.
• Hardness: It has a hardness of 3 on the Mohs scale, which means it is relatively soft and can be easily scratched with a knife.
• Luster: Calcite has a vitreous to pearly luster.
• Crystal Form: It commonly occurs in rhombohedral or scalenohedral crystals, but can also be found in massive or granular forms.

Optical Properties

• Refractive Index: Calcite has a high birefringence, meaning it can split a light beam into two beams and produce double refraction.
• Optical Sign: It is a uniaxial negative mineral, which means it has one optic axis and is capable of producing a single image when viewed through a polarizing microscope.

Formation and Occurrence

Calcite forms in a variety of geological settings, including sedimentary environments such as limestone and marble formation, hydrothermal veins, and as a secondary mineral in igneous rocks.

Uses

Calcite has many industrial uses, including as a building material, in the production of lime and cement, as a soil conditioner, in the manufacture of glass and ceramics, and as a source of calcium carbonate for pharmaceuticals and dietary supplements.

Study Tips

• Learn to identify calcite based on its physical properties such as color, hardness, and crystal form.
• Understand the optical properties of calcite, including its birefringence and optical sign.
• Explore the various geological settings in which calcite forms and the processes involved in its formation.
• Research the industrial uses of calcite and its importance in various industries.