MINERAL: APATITE
Chemical composition:
Apatite is a group of phosphate minerals, composed mainly of calcium, phosphate, and fluorine, chlorine, or hydroxyl, with the general chemical formula Ca5(PO4)3(F, Cl, OH).
Physical properties:
Color: Apatite can be colorless, yellow, green, blue, violet, pink, or brown.
Luster: Apatite has a vitreous or greasy luster.
Transparency: Apatite can be transparent to opaque.
Crystal habit: Apatite typically forms as hexagonal or elongated crystals, sometimes with a square or rectangular cross-section.
Hardness: Apatite has a Mohs hardness of 5.
Specific gravity: Apatite has a specific gravity of 3.1-3.2.
Cleavage: Apatite has perfect cleavage in one direction.
Fracture: Apatite has a conchoidal fracture.
Magnetic properties: Apatite is not magnetic.
Thermal conductivity: Apatite has a low thermal conductivity.
Optical properties:
Refractive index: Apatite has a refractive index of 1.6-1.64.
Optic sign: Apatite is uniaxial positive
Dispersion: Apatite has a low dispersion.
Pleochroism: Apatite exhibits weak pleochroism, with different colors appearing in different orientations.
Birefringence: Apatite has a low birefringence of about 0.009.
Extinction: Apatite has an extinction angle of about 20-30 degrees.
Interference colors: Apatite typically exhibits first-order gray or yellow interference colors.
Relief: Apatite has a low relief.
Optic axis: Apatite has a single optic axis.
Uses:
Apatite is not a commonly used mineral, but it is used as a source of phosphorus, as a mineral specimen by collectors, and as a gemstone.
Apatite is also used in the production of fertilizers, phosphoric acid and as a mineral indicator for certain geologic processes.
Fluorapatite is used in the production of fluoride, and hydroxyapatite is used in the production of toothpaste and bone replacement materials.
Please note that these properties can vary depending on the exact composition and impurities present in the mineral specimen.
Source: Internet