The Differences Between Fluorite & Calcite

Fluorite and calcite, two mineral types, are vastly different in shape and behavior. For example, fluorite grows using a symmetrical crystal system, while calcite forms asymmetrically. Calcite is considered a common mineral, while fluorite is a semiprecious mineral. The two are found in vastly different environments and locations throughout the world.

Fluorite is a type of mineral in an isometric formation. This means crystals form symmetrical cubes as they grow, so the mineral itself is often found in symmetrical chunks — though the corners have often been compromised through natural wear. Fluorite forms in hot springs deposits, cavities in sedimentary rocks and in hydrothermal veins. On the Mohs hardness scale, fluorite is rated a four.

The mineral calcite forms in a trigonal hexagonal calenohedral crystal system, making calcite specimens resemble a double-ended pyramid. This species of mineral forms in sedimentary, igneous and metamorphic rock types, and often forms large slabs in limestone and marble. Calcite has a hardness rating of three on the Mohs hardness scale.

Calcite and fluorite also differ in behavior attributes. For example, fluorite has a melting point of 1360 degrees Celsius, while calcite melts at 1612 degrees Celsius. Both calcite and fluorite will fluoresce under certain light conditions, though only fluorite is also phosphorescent. Some forms of fluorite also glow when exposed to certain forms of electromagnetic energy then heated — a process known as thermoluminescence, while calcite does not.

Another difference between calcite and fluorite is the color each forms in. Calcite is known to be various shades of white, yellow, red, orange and most earth tones. Fluorite on the other hand, has been found in shades of purple, golden-yellow, green, blue, pink, champagne, brown, as well as colorless forms. Calcite has been found in over 800 morphological forms, while fluorite usually appears in cubes, octahedrons and dodecahedrons.