Sylvite

sylvite: see potassium chloride.

---

sylvite [′sil‚vīt]

(mineralogy)

KCl A salty-tasting, white or colorless isometric mineral, occurring in cubes or crystalline masses or as a saline residue; the chief ore of potassium. Also known as leopoldite; sylvine.

---

Sylvite 

a mineral of the halide class with chemical composition KC1. It contains 52.48 percent K and admixtures of Br and, less frequently, I. Occluded gas bubbles (N₂, CO₂, CH₄, He) impart a milky white color to transparent and colorless sylvite crystals. Sylvite also contains admixtures of halite (NaCl) and ferric oxide (Fe₂ O₃), the latter giving the mineral a red color.

Sylvite crystallizes in the isometric system. Distinct well-cut crystals are rare. Sylvite usually forms compact granular masses with, for example, halite and carnallite (similar aggregates are called sylvinite). Sylvite has a hardness of 2 on Mohs scale, a density of 1,990 kg/m³, and a vitreous, dull luster. It dissolves freely in water andhas a burning, bitter salty taste. Transparent crystals exhibit good transmission of radiation in the shortwave and infrared regions of the spectrum.

Sylvite naturally occurs in sedimentary salt-bearing rock strata together with halite and carnallite, sometimes forming large strata in the commercial deposits of potassium salts. It also occurs as a sublimation product of volcanic fumes. Artificial transparent sylvite crystals are used in the optical systems of spectrographs and other devices.