Feldspar
Anorthite
Miyake Island, Miyake Subprefecture, Tokyo Metropolis, Japan
0.52 carats
© Stefan Ix
There are two main subgroups that produce gems: the potassium feldspars and the plagioclases (a series from calcium to sodium feldspars).
Feldspar Gemstones by Colour
This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
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Feldspar Gemstones by Size
This table shows distribution of Feldspar gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.52 cts
Heaviest:21.50 cts
Average:5.60 cts
Total photos:75
Do you have a larger Feldspar? Why not upload a photo?
| General Information | |
|---|---|
| Varieties/Types: | Albite - Sodium-rich Feldspar. Andesine - A plagioclase feldspar with an Albite: Anorthite molar ratio ranging from 50:50 to 70:30. Oligoclase - A plagioclase feldspar with an Albite: Anorthite molar ratio ranging from 90:10 to 70:30. Anorthite - Calcium-rich Feldspar. Bytownite - A plagioclase Feldspar with an Albite: Anorthite molar ratio ranging from 10:90 to 30:70. Labradorite - A plagioclase Feldspar with an Albite: Anorthite molar ratio ranging from 30:70 to 50:50. Microcline - A triclinic Potassium Feldspar. Amazonite - A green to blue-green variety of Microcline. Orthoclase - A monoclinic Potassium Feldspar. Moonstone - A variety of Orthoclase that exhibits a strong blue adularescence. Sanidine - A triclinic Potassium Feldspar found in lavas. Sunstone - A Plagioclase Feldspar, which exhibits aventurescence when viewed from certain directions. |
| Physical Properties of Feldspar | |
| Mohs Hardness | 6 to 6.5, Gemstones of the world (2001) |
| Specific Gravity | 2.56 to 2.75, Gemstones of the world (2001) |
| Cleavage Quality | Perfect, Gemstones of the world (2001) |
| Fracture | Uneven,Conchoidal,Splintery, Gemstones of the world (2001) |
| Optical Properties of Feldspar | |
| Refractive Index | 1.518 to 1.570, Gemstones of the world (2001) |
| Birefringence | 0.008 to 0.010, Gemstones of the world (2001) |
| Colour | |
| Colour (General) | Colourless, yellow, green, blue-green, orange, red-brown, dark gray, gray-black., Gemstones of the world (2001) |
| Transparency | Transparent,Translucent,Opaque, Gemstones of the world (2001) |
| Further Information | |
| Mineral information: | Feldspar information at mindat.org |