Fluorite is very easy to identify if you consider cleavage, hardness, and specific gravity. It is the only common mineral that has four directions of perfect cleavage, often breaking into pieces with the shape of an octahedron. It is also the mineral used for a hardness of four in the Mohs Hardness Scale. Finally, it has a specific gravity of 3.2, which is detectably higher than most other minerals.

Although color is not a reliable property for mineral identification, the characteristic purple, green, and yellow translucent-to-transparent appearance of fluorite is an immediate visual clue for the mineral.

What is a Fluorite Lens?

Fluorite is a naturally occurring substance, which just so happens to possess near perfect light dispersion qualities. These qualities mean that they are a good choice for use in optical equipment, for where ultra high quality is a must. For this reason, fluorite has been used in optical equipment, such as microscopes, since the 1920’s.

The only problem is that fluorite can not be harvested in sufficient quantity and quality in the natural environment. Canon’s engineers found a way around this issue, by synthetically growing fluorite crystals in a laboratories. Even then, it is still a very complex job to turn Fluorite in to a lens product. For this reason, Fluorite lens elements are only found in the very best Canon lenses, such as the EF 100-400mm F4-5.6 L USM II.

Fluorite carving

Fluorite is a fantastic mineral that grows in cubic crystals in a whole wide array of colors, in both visible light and ultraviolet light. Its earliest uses date back to the ancient Egyptians and Chinese. It sees wide use as an ornamental stone and is a favorite of collectors. It is too soft to be a semiprecious gemstone, but it is often carved and shaped into beautiful beads and other creations.

Fluorite wasn’t mined for commercial reasons until 1933.The largest single fluorite crystal cube was found in Russia and reportedly measured 2.12 meters in size, weighing 16 tons.