Feldspar

Moonstone
Myanmar
4.57 carats
© Palagems

Feldspar is derived from German "Feld"- field and "Spath" - a rock that does not contain ore.

There are two main subgroups that produce gems: the potassium feldspars and the plagioclases (a series from calcium to sodium feldspars).

313 photos

Feldspar Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.

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:0.07 cts

Heaviest:145.2 cts

Average:9.07 cts

Total photos:305

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0.07ct to 14.58ct14.58ct to 29.10ct29.10ct to 43.61ct43.61ct to 58.12ct58.12ct to 72.64ct72.64ct to 87.15ct87.15ct to 101.66ct101.66ct to 116.17ct116.17ct to 130.69ct130.69ct to 145.20ct

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. 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. Spectrolite - Trade name for a Labradorite from Finland that shows the spectral colours especially effectively. Microcline - A triclinic Potassium Feldspar. Amazonite - A green to blue-green variety of Microcline. Oligoclase - A plagioclase feldspar with an Albite: Anorthite molar ratio ranging from 90:10 to 70:30. Orthoclase - A monoclinic Potassium Feldspar. Adularia - A gemmy colourless variety of Orthoclase. 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 Walter Schumann, Gemstones of the world (2001)
Specific Gravity	2.56 to 2.75 Walter Schumann, Gemstones of the world (2001)
Cleavage Quality	Perfect Walter Schumann, Gemstones of the world (2001)
Fracture	Uneven,Conchoidal,Splintery Walter Schumann, Gemstones of the world (2001)
Optical Properties of Feldspar
Refractive Index	1.518 to 1.570 Walter Schumann, Gemstones of the world (2001)
Birefringence	0.008 to 0.010 Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)	Colourless, yellow, green, blue-green, orange, red-brown, dark gray, gray-black. Walter Schumann, Gemstones of the world (2001)
Transparency	Transparent,Translucent,Opaque Walter Schumann, Gemstones of the world (2001)
Further Information
Mineral information:	Feldspar information at mindat.org

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