Sylvite

Sylvite

Sylvite
General
Category Halide mineral
Formula
(repeating unit)		 KCl
Strunz classification 3.AA.20
Crystal system Isometric
Unit cell a = 6.2931 Å; Z = 4
Identification
Formula mass 74.55 g
Color

Colorless to white, pale gray, pale blue; may be yellowish red

to red due to hematite inclusions
Crystal habit As cubes and octahedra; columnar, in crusts, coarse granular, massive
Crystal symmetry Isometric - hexoctahedral
H-M symbol (4/m32/m)
Space group: F m3m
Cleavage Perfect on [100], [010], [001]
Fracture Uneven
Tenacity Brittle to ductile
Mohs scale hardness 2
Luster Vitreous
Streak white
Diaphaneity Transparent to translucent
Specific gravity 1.993
Optical properties Isotropic
Refractive index 1.4903
Pleochroism Visible in colored crystals
Ultraviolet fluorescence None
Solubility Soluble in water
Other characteristics salty to bitter taste
References [1][2][3]

Sylvite, or sylvine, is potassium chloride (KCl) in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite (NaCl). The two are, in fact, isomorphous.[4] Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific gravity of 1.99. It has a refractive index of 1.4903.[5] Sylvite has a salty taste with a distinct bitterness.

Sylvite is one of the last evaporite minerals to precipitate out of solution. As such, it is only found in very dry saline areas. Its principal use is as a potassium fertilizer.

Sylvite
Sylvite from Germany

Sylvite is found in many evaporite deposits worldwide. Massive bedded deposits occur in New Mexico and western Texas, and in Utah in the US, but the largest world source is in Saskatchewan, Canada. The vast deposits in Saskatchewan, Canada were formed by the evaporation of a Devonian seaway. Sylvite is the official mineral of Saskatchewan.

Sylvite was first described in 1832 at Mt. Vesuvius near Napoli in Italy and named for the Dutch chemist, François Sylvius de le Boe (1614–1672).[1]

Sylvite, along with quartz, fluorite and halite, is used for spectroscopic prisms and lenses.[6]

See also

References

  1. 1 2 Sylvite: Sylvite mineral information and data
  2. ↑ Sylvite Mineral Data
  3. ↑ Handbook of Mineralogy
  4. ↑ Klein, Cornelis and Cornelius S. Hurlbut, Jr. 1993. Manual of Mineralogy after J.D. Dana, 21st edition. New York: John Wiley & Sons, Inc.
  5. ↑ Deer, W.A., R.A. Howie, and J. Zussman. 1992. An Introduction to the Rock-Forming Minerals 2nd ed. New York: Prentice Hall.
  6. ↑ "Motz, Lloyd. "Spectroscopy." Microsoft® Encarta® 2009" S (2009): 1841.

External links

 Chisholm, Hugh, ed. (1911). "Sylvite". Encyclopædia Britannica (11th ed.). Cambridge University Press. 

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