Moonstone
Moonstone is colourless, very translucent, or almost perfectly transparent feldspar, which in certain direction reflects a bluish, milky light, that has been compared to the light of the moon.
Moonstone is a potassium feldspar of the orthoclase species with white shimmer, similar to moonshine (therefore the name), called adularescence. Thin alternating layers of
orthoclase and
albite create the light interference in this material that is responsible for its "shiller" or "floating moon effect".
Only specimens which show this sheen in a typical manner are cut as gems. To display the beauty of this stone to the best possible advantage , it is cut with a convex, polished surface of moderately strong curvature about the face which exhibits the sheen. The stone is very effective in cut and polished spheres, which may be strung together and worn as beads or for other ornamental purposes, when they have a certain resemblance to white pearls. Moonstone is always cut either en cabochon or with a plane surface, never with facets.
General Information |
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A variety or type of: | Orthoclase, which is a variety of Feldspar |
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Other Names/Trade Names: | |
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Chemical Formula | Walter Schumann, Gemstones of the world (2001) |
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Photos of natural/un-cut material from mindat.org |
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Moonstone Simulants |
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Imitated by adularescent synthetic spinel (possibly with mirror-like back coating), milky chalcedony, glass - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 8 |
Physical Properties of Moonstone |
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Mohs Hardness | 6 to 6.5Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Specific Gravity | 2.56 to 2.60Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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Cleavage Quality | PerfectUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Fracture | Uneven,ConchoidalWalter Schumann, Gemstones of the world (2001) |
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Optical Properties of Moonstone |
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Refractive Index | 1.518 to 1.527Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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Optical Character | Biaxial/-Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Birefringence | 0.006 to 0.007Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Pleochroism | AbsentWalter Schumann, Gemstones of the world (2001) |
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Dispersion | NoneWalter Schumann, Gemstones of the world (2001) |
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Colour |
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Colour (General) | Colourless, white, adularescent with a silvery or bluish sheen, green, brownish, reddish.Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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Transparency | Transparent,TranslucentUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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Lustre | VitreousWalter Schumann, Gemstones of the world (2001) |
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Fluorescence & other light emissions |
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Fluorescence (General) | Weak; bluish, orangeWalter Schumann, Gemstones of the world (2001) |
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Fluorescence (Short Wave UV) | Inert to orangy-(reddish)Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Fluorescence (Long-Wave UV) | Inert to blue (and pinkish)Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Crystallography of Moonstone |
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Crystal System | MonoclinicUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Habit | PrismaticWalter Schumann, Gemstones of the world (2001) |
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Geological Environment |
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Where found: | The most prominent source is in the gravels and pegmatitesMichael O’Donoghue, Gems, Sixth Edition (2006) |
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Inclusions in Moonstone |
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Typical "centipede" inclusions - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 8
Healing cracks, crystal inclusions, cleavage cracks - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 5 |
Further Information |
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Mineral information: | Moonstone information at mindat.org |
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Significant Gem Localities |
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| Myanmar | |
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| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
- Dattaw-taung (Dattaw hill)
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
- Pein-Pyit (Painpyit; Pyan Pyit)
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok | | Sri Lanka | |
| Gemexplorer.org |
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