Fluorite

Hardness: 4 on Mohs scale; Color: Wide range including colorless, blue, green, purple, yellow, pink, and black. Often banded or color-zoned, as seen in the image with blue and light blue/clear zones; Luster: Vitreous (glassy); Crystal Structure: Isometric (cubic, octahedral, or dodecahedral forms are common); Cleavage: Perfect octahedral cleavage (breaks into eight-sided pyramid shapes); Specific Gravity: 3.17-3.18

Fluorite commonly forms in hydrothermal veins, often associated with metallic ores (e.g., lead, zinc, silver). It can also be found in sedimentary rocks, such as limestones and dolostones, and in some igneous rocks. Its formation is typically at relatively low temperatures.

Industry: Used as a flux in steelmaking (where its name 'fluorspar' comes from, meaning 'to flow'), in the production of hydrofluoric acid for various chemical industries (e.g., refrigerants, aluminum), and in optical lenses due to its low dispersion. Jewelry: Used in carvings and ornamental objects; however, its low hardness makes it less suitable for everyday wear. Collecting: Highly prized by mineral collectors for its vibrant colors and well-formed crystals.

Fluorite is known for its strong fluorescence under ultraviolet light (the phenomenon of fluorescence takes its name from fluorite). It can also exhibit thermoluminescence (emitting light when heated) and triboluminescence (emitting light when scratched or rubbed). The distinct color banding seen in the specimen is common and highly sought after by collectors.

In the field, fluorite can be identified by its relative softness (easily scratched by a knife but not a fingernail), its perfect octahedral cleavage, and its wide range of colors, often with banding. Crystal forms (cubes, octahedra) are also a strong indicator. It is commonly found worldwide, with significant deposits in China, Mexico, Mongolia, and various locations in the USA (e.g., Illinois, Kentucky, New Mexico).