Moonstone (gemstone)

Source: Wikipedia, the free encyclopedia.
Not to be confused with Moon rock.
For other uses, see Moonstone (disambiguation).
Moonstone
Specific gravity
2.54–2.66
Optical propertiesfor orthoclase and sanidine, biaxial (–); for oligoclase, biaxial +/–
Refractive index1.518–1.547
Birefringence0.005–0.01
Dispersion0.012
A small rough moonstone sample

Moonstone is a

silicate ((Na,K)AlSi3O8) of the feldspar group that displays a pearly and opalescent schiller.[1][2] An alternative name for moonstone is hecatolite[2] (from goddess Hecate
).

Etymology

The name moonstone derives from the stone's characteristic visual effect, called

exsolution layers (lamellae) of different alkali feldspars
(orthoclase and sodium-rich plagioclase).

Polished moonstones often display chatoyancy ("cat's eye" effect), where a luminous streak appears through the stone. Asterism is rare and produces four-legged stars.[1]

Geology

Moonstone cabochon

The most common moonstone is of the

better source needed] A solid solution of the plagioclase feldspar oligoclase +/− the potassium feldspar orthoclase also produces moonstone specimens
.

Deposits of moonstone occur in Armenia (mainly from Lake Sevan), Australia, the Austrian Alps, Mexico, Madagascar, Myanmar, Norway, Poland, India, Sri Lanka, and the United States.[2][3] Historically, the most valuable, transparent moonstones with strong blue sheen came from Myanmar.[1] Today, most commercial moonstones come from Sri Lanka.[3]

In culture

Moonstone has been used in jewellery for millennia, including ancient civilizations. The Romans admired moonstone, as they believed it was derived from solidified rays of the Moon.[4] Both the Romans and Greeks associated moonstone with their lunar deities. In more recent history, moonstone became popular during the Art Nouveau period; French goldsmith René Lalique and many others created a large quantity of jewellery using this stone.[5]

The moonstone is the Florida State Gemstone; it was designated as such in 1970 to commemorate the Moon landings, which took off from Kennedy Space Center. However, it does not naturally occur in the state.[6]

References

  1. ^ a b c d e Moonstone Gemological Information International Gem Society, Retrieved 01-05-15
  2. ^ a b c Moonstone, Mindat.org, retrieved 2022-02-06
  3. ^ a b "Moonstone" Encyclopædia Britannica, 2011. Web. 20 Jan. 2011.
  4. ^ "Moonstone" American Gem Trade Association. Retrieved 21 January 2011.
  5. ^ "Moonstone" International Colored Gemstone Association. Retrieved 26 April 2012.
  6. ^ "Moonstone – Florida State Symbols". Florida Division of Historical Resource. Retrieved 1 Sep 2011.

External links

  • Media related to Moonstone at Wikimedia Commons
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