Moonstone (gemstone)

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Not to be confused with Moon rock.
Moonstone
AdulaireSuisse2.jpg
General
Category Feldspar variety
Identification
Color Can be numerous colors, including blue, grey, white, pink, peach, green and brown
Fracture uneven to conchoidal
Mohs scale hardness 6.0
Luster Opalescent
Streak white
Specific gravity 2.61

Moonstone is a sodium potassium aluminium silicate, with the chemical formula (Na,K)AlSi3O8.

Etymology[edit]

Its name is derived from a visual effect, or sheen, caused by light diffraction within a microstructure consisting of a regular succession of feldspar layers.

History[edit]

Moonstone has been used in jewelry for centuries, including ancient civilizations. The Romans admired moonstone, as they believed it was born from solidified rays of the moon.[1] Both the Romans and Greeks associated Moonstone with their lunar deities. In more recent history, the moonstone became popular during the Art Nouveau period; French goldsmith René Lalique and many others created a large quantity of jewelry using this stone.[2]

Geology[edit]

The most common moonstone is of the mineral adularia. The plagioclase feldspar oligoclase also produces moonstone specimens. Moonstone is feldspar with a pearly and opalescent luster.[3] An alternative name is hecatolite.[3]

Formation[edit]

Moonstone is composed of two feldspar species, orthoclase and albite. The two species are intermingled. Then, as the newly formed mineral cools, the intergrowth of orthoclase and albite separates into stacked, alternating layers. When light falls between these thin, flat layers, it scatters in many directions producing the phenomenon called adularescence.

Occurrence[edit]

Polished cabochon

Deposits of moonstone occur in Australia, the Austrian Alps, Mexico, Madagascar, Burma, Norway, Poland, India, Sri Lanka[4] and the United States.[3]

It is currently the state gem for Florida.[5]

References[edit]

  1. ^ "Moonstone" American Gem Trade Association. Retrieved 21 January 2011.
  2. ^ "Moonstone" International Colored Gemstone Association. Retrieved 26 April 2012.
  3. ^ a b c http://www.mindat.org/min-2774.html Mindat.org
  4. ^ "Moonstone" Encyclopædia Britannica, 2011. Web. 20 Jan. 2011.
  5. ^ "Moonstone - Florida State Symbols". Florida Division of Historical Resource. Retrieved 1 Sep 2011.