Cryolite


MINERAL : CRYOLITE

Cryolite is an Sodium Aluminum Fluoride-Na3AlF6. It is named from the Greek word kryos means frost and lithos means stone. Cryolite is a very uncommon mineral with very little deposit on the earth crust found so far. Cryolite has low refractive index which is very near to the water. Due to this nature of cryolite immerses with water making it a perfectly clear crystal. Powder cryolite will completely disappear with water. It crystallizes with monoclinic system.


OCCURRENCE AND DEPOSITS

Cryolite is found in the pegmatite porphyritic granite associated with many other substances like fluorite, siderite, pyrite, arsenopyrite, galena, topaz and molybdenite etc. This type of cryolite is found in Ivigtut of south Greenland. After mining cryolite is sent to USA and Denmark for processing. Cryolite is also deposited under lease by kryolit seleskabet oresund, Copenhagen Denmark. Cryolite is also found at the foot of pikes of Creede, Colorado USA, Mont Saint-Hilaire and Francon Quarry, Montreal, Quebec Canada and Miask Russia.


PROPERTIES

  • Colorless to white, also sometimes black, reddish and brown.
  • Crystal system is monoclinic.
  • Crystal habit of cryolite is massive, and granular.
  • Its luster is vitreous and greasy.
  • Cryolite crystals are transparent to translucent.
  • Its cleavage is absent but it looks like pseudo-cubic cleavage.
  • Streak is white.
  • Its hardness is between 2.5 to 3.
  • Its luminescence is fluorescent and short UV- bluish white.
  • Specific gravity is 2.95 to 3.
  • Cryolite is a brittle.
  • Its fracture is uneven.
APPLICATIONS/ USES
  • Cryolite is used as a solvent of aluminum rich ore and bauxite which is the combinations of aluminum oxides.
  • It is used in the aluminium metallurgy where it is used as an electrolyte in the reduction of alumina to aluminum metal by Hall process.
  • It is also used as one of the bonding agents in grinding wheels and abrasives.
QUESTION AND ANSWERS
  1. What is the chemical foremula of cryolite?
Ans : Cryolite is an Sodium Aluminum Fluoride-Na3AlF6 .
  1. In which country cryolite deposition is abunbdantly available?
Ans : Greenland
  1. Mention some important properties of cryolite?
Ans : Crystal habit of cryolite is massive, and granular. Its luster is vitreous and greasy. Its hardness is between 2.5 to 3.
  1. Give 2 applications of cryolite?
Ans : Cryolite is used as a solvent of aluminum rich ore and bauxite which is the combinations of aluminum oxides. It is used in the aluminium metallurgy where it is used as an electrolyte in the reduction of alumina to aluminum metal by Hall process.

REFERENCES:

www.wikipedia.com
www.midat.com
www.galleries.com

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