Moonstone (gemstone)


Moonstone (gemstone)
Moonstone
General
Category Feldspar variety
Identification
Color Can be numerous colors, including blue, grey, white, pink, 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.

Contents

Etymology

Its name is derived from a visual effect, or sheen, caused by light reflecting internally in the moonstone from layer inclusion of different feldspars.

History

Moonstone has been used as 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 gods and goddesses.

Geology

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.[2] An alternate name is hecatolite.[2]

Formation

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

Deposits of moonstone occur in Australia, the Austrian Alps, Mexico, Madagascar, Burma, Norway, Poland, Sri Lanka[3] and the United States.[2]

It is currently the state gem for Florida.[4]

References

  1. ^ "Moonstone" American Gem Trade Association. Retrieved 21 January 2011.
  2. ^ a b c http://www.mindat.org/min-2774.html Mindat.org
  3. ^ "Moonstone" Encyclopædia Britannica, 2011. Web. 20 Jan. 2011.
  4. ^ "Moonstone - Florida State Symbols". Florida Division of Historical Resource. http://www.flheritage.com/kids/symbol.cfm?id=17. Retrieved 1 Sep 2011.