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moonstone,an orthoclase feldsparfeldspar
, an abundant group of rock-forming minerals which constitute 60% of the earth's crust. Chemically the feldspars are silicates of aluminum, containing sodium, potassium, iron, calcium, or barium or combinations of these elements.
..... Click the link for more information. , found in Sri Lanka, Myanmar, and Madagascar (and formerly in the St. Gotthard district of Switzerland). In spite of its pronounced cleavage, it is widely used as a gemgem,
commonly, a mineral or organic substance, cut and polished and used as an ornament. Gems also are used as seals (items of assurance) and as talismans (good-luck charms). For birthstones, see month.
..... Click the link for more information. . The refraction of light by its thin, paired internal layers causes its milky, bluish sheen.
a semitransparent variety of orthoclase (adularia) and sometimes plagioclase (albite or oligoclase). Moonstone displays a bluish iridescence. It is occasionally found in pegmatites or alpine-type veins. It is used as a decorative stone for insets and small ornaments. The best moonstone with respect to quality and color is found in Sri Lanka; in the USSR it is found in the pegmatite veins of Karelia.