Composition: Silicates containing one or more of: barium, calcium, potassium, sodium, strontium, aluminum, or boron.
Nomenclature: Named after the German term felt spat which means "field spar" because of the wide distribution of its occurrence.
Industrial Uses: Crushed stone, some gemstones (such as moonstone).
Additional Notes: Feldspar is a group of chemically- and structurally-related minerals which, taken together, comprise the most common minerals on Earth. Feldspar is also (less frequently) referred to as feldspath and felspar. Over time, feldspar weathers and decomposes into clay.
French Southern and Antarctic Territories : Scott 212 : 1.00 franc : 1 Jan 1996
Microcline var. amazonite (feldspar)
Kenya : Scott 101 : 40 cents : 13 Dec 1977
Microcline var. amazonite (feldspar)
Malawi : Scott 371 : 10 tambala : 20 Aug 1980
Sunstone (oligoclase feldspar)
Monaco : Scott 1724 : 2.30 franc : 4 Sep 1990
Albite (feldspar)
New Caledonia : Scott 473 : 30 francs : 17 Mar 1982
Anorthosite (feldspar); Nephrite (jade); Serpentine
Switzerland : Scott B293 : 10+10 centimes : 1 Jun 1960
Feldspar
Uganda : Scott 606 : 150 shilling : 18 Jan 1988
Microcline var. amazonite (feldspar)