#fluores

The symmetry of fluorite can produce several different shapes, depending on how the crystal grows. High temperature flourites, grown from fluids coming off of magma bodies, tend to form octahedral like these. Low temperature flourites, grown from fluids moving through sedimentary rocks, often form true cubes. The difference in shape relates to which faces grow fastest and easiest under the temperature of growth. Obviously from this image, the colors of the different crystals are different. Pure fluorite is actually colorless, but fluorite can have a large variety of colors depending on tiny amounts of other elements that get stuck into it and whether or not they have been irradiated over time in the ground. The yellow fluorites, for example, likely get their color from manganese substituted for the calcium. Fluorite is commonly mined as an industrial mineral. Fluorine is highly reactive and so it is used in all sorts of products, including in the production of hydrofluoric acid, which is an extremely powerful substance for dissolving and etching solids that can be lethal to humans with just skin exposure. Fluorine is also used as a flux, meaning it is added to materials to help lower the melting temperature. This is particularly true for smelting aluminum; aluminum oxide has to be molten to allow it to be converted into aluminum metal, but it has an extremely high melting temperature, so adding fluorine allows it to be melted at more reasonable temperatures. The original term fluores translates as “to flow”, and so fluorite is a material that, when you add it to something, allows it to flow. -JBB Image credit: https://flic.kr/p/7Er9h References: http://www.fluoride-history.de/fluorine.htm https://www.lpi.usra.edu/meetings/gold2001/pdf/3887.pdf