Peridot
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Peridot , also called chrysolite , is a particularly pure variety of the mineral olivine . The light green, transparent mineral is used as a gem stone .
Peridot is the magnesium-rich type of olivine ( forsterite ) with a composition that approximates Mg 2 SiO 4 . Its crystals are orthorhombic and its hardness is slightly less than that of quartz .
Surname
The origin of the name "Peridot", which appeared in many variations in the English and French-speaking areas in the Middle Ages, is unclear. Possible origins include the Latin paederos (" opal ") and the Arabic faridat ("precious stone").
"Beryl" ( "Goldstein", "golden gem."; From the Greek Chrysos , gold, and lithos , stone) in ancient times was usually the name of yellow quartz ( gold topaz ). Later, it became a mineralogical collective term, which is no longer in use today, for gemstones with green-gold reflections, especially (since the Middle Ages) peridot, but also prehnite and apatite varieties .
Occurrence
While olivine is a widely used mineral, gem-quality peridot is rare - a result of the mineral's chemical instability at the earth's surface. Small peridot crystals are also found in volcanic basalt and in meteorites .
The earliest known peridot mining occurred around the year 70 on St. John's Island in the Red Sea . Most of the early peridot stones came from there, and a small amount of peridot is still mined there today. Later, large peridot stones (20 to 40 carats ) of excellent quality were mined, especially in Myanmar (Burma) , but exports have largely come to a standstill since the country's independence.
Most of the peridot is mined in the US today, valued at $ 1.3 million in 1993, for example. 80% to 95% of the peridot used worldwide comes from the Peridot Mesa in the San Carlos Apache Indian Reservation in Arizona . Other US deposits can be found in New Mexico (Buell Park, Kilbourne Hole and Potrillo Mar). Additional peridot mining areas include other locations in the United States, China, Sri Lanka and Pakistan, where new deposits were discovered in 1994.
Use as a gem stone
Peridot is light green in color, varying from yellow-green to olive-green. However, brownish varieties are also known. Peridot is sometimes confused with emerald and other green gemstones such as chrysoberyl , diopside , moldavite as well as garnet ( demantoid ), quartz ( prasiolite , prasem ) and tourmaline varieties ( cromolite , verdelite ).
Peridot (as pitdah ) is already mentioned in the Old Testament , and in ancient Rome the stone was valued as "evening emerald" because it can be easily illuminated by lamplight. In the Middle Ages, peridot was often part of church decorations; Peridot stones were probably brought to Europe by crusaders . Healing powers were ascribed to the stone, as well as the power to drive away evil spirits.
literature
- Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 174 .
Web links
Individual evidence
- ^ A b c d e Peridot , Michael W. Davidson, National High Magnetic Field Laboratory , Florida State University
- ↑ Bernhard Dietrich Haage: Studies on medicine in the "Parzival" Wolframs von Eschenbach (= Göppingen work on German studies . 565). Kümmerle, Göppingen 1992, ISBN 3-87452-806-5 , pp. 105 f .; Hugo Blümner : Chrysolithos . In: Paulys Realencyclopadie der classischen Antiquity Science (RE). Volume III, 2, Stuttgart 1899, Col. 2516.
- ^ Urban T. Holmes: Mediaeval gemstones. In: Speculum . Vol. 9, No. 2, 1934, pp. 195-204, here pp. 199 f., JSTOR 2846596
- ^ A b Peridot , US Geological Survey Minerals Information, US Department of the interior
- ^ Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 174 .