Sylvite
Potassium chloride mineral used as fertilizer and historically in infrared optics.
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Sylvite, also known as sylvine, is the natural mineral form of potassium chloride (KCl). It crystallizes in the isometric system, a structure it shares with common rock salt (halite, NaCl); the two minerals are isomorphous, meaning they have the same crystal form. In appearance, sylvite is typically colorless to white, though it can exhibit shades of yellow or red due to inclusions of other materials.
It is a relatively soft mineral, with a Mohs hardness of 2.5, and has a specific gravity of 1.99. Its refractive index is 1.4903. A distinctive characteristic is its taste, which is salty but with a notable bitterness.
Sylvite forms as an evaporite mineral, being one of the last substances to precipitate from a saline solution as water evaporates. Consequently, it is found only in very dry, saline environments. Its principal use is as a potassium fertilizer. The mineral occurs in many evaporite deposits around the world.
In the United States, massive bedded deposits are found in New Mexico, western Texas, and Utah. However, the largest known source globally is in Saskatchewan, Canada, where vast deposits formed from the evaporation of an ancient Devonian seaway. Sylvite is recognized as the official mineral of Saskatchewan.
Beyond its agricultural role, sylvite has applications in optics, where it is used alongside quartz, fluorite, and halite for making spectroscopic prisms and lenses. The mineral was first described scientifically in 1832 at Mount Vesuvius near Naples, Italy. Its name derives from historical designations for potassium chloride, sal digestivum Sylvii and sal febrifugum Sylvii, which themselves honor the Dutch physician and chemist François Sylvius de le Boe (1614–1672).
Lore & Background
Sylvite appears as crystals in the isometric system, closely resembling halite in form, and is colorless to white, often displaying yellow or red shades caused by inclusions. It has a Mohs hardness of 2.5, a specific gravity of 1.99, and a refractive index of 1.4903. The mineral possesses a salty taste with a notable bitterness. As one of the last evaporite minerals to crystallize from solution, it occurs only in very dry saline environments.
Sylvite is found in numerous evaporite deposits globally, with massive bedded deposits in New Mexico, western Texas, and Utah in the United States, while the largest world source lies in Saskatchewan, Canada, where the deposits formed from the evaporation of a Devonian seaway. It is the official mineral of Saskatchewan. First described in 1832 at Mount Vesuvius near Naples, Italy, it was named after historical designations for potassium chloride, which themselves honored the Dutch physician and chemist François Sylvius de le Boe. Beyond its principal use as a potassium fertilizer, sylvite is employed alongside quartz, fluorite, and halite for spectroscopic prisms and lenses.
Reader's Guide
Sylvite is significant primarily as a source of potassium for fertilizer, being one of the last evaporite minerals to precipitate from solution, thus found only in very dry saline areas. Its massive bedded deposits occur in New Mexico, western Texas, and Utah in the US, but the largest world source is in Saskatchewan, Canada, where the deposits formed from the evaporation of a Devonian seaway. Beyond agriculture, sylvite is used along with quartz, fluorite, and halite for spectroscopic prisms and lenses. The mineral's naming honors François Sylvius de le Boe, reflecting its historical chemical associations.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Sylvite (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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