Formula: KCl
Chloride, halite group
Crystal System: Isometric
Specific gravity: 1.993 measured, 1.987 calculated
Hardness: 1½ to 2
Streak: White
Colour: Colourless, grey, white, yellowish to reddish, seldom blue or violet
Common impurities: Br,CO2=C,O
Environments:
Evaporite Deposits
Volcanic sublimates
Coal-seam fires
Sylvite occurs in sedimentary basins, forming thick bedded deposits with
halite, also as a sublimate in volcanic fumaroles, in which it is a predominant
precipitate at 550°C; it occurs in nitrate beds and in cave deposits; it is also a product of burning coal, and it may
be included in other minerals as a product of intermediate-grade metamorphism. Associated minerals include
halite, kieserite,
kainite, carnallite,
polyhalite, gypsum and
anhydrite
HOM, (Mindat).
Localities
The type locality is Mount Vesuvius, Metropolitan City of Naples, Campania, Italy.
Sylvite from Vesuvius Fumeroles - Image
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