Red beryl
| Red beryl | |
|---|---|
 |
|
| General and classification | |
| other names |
Bixbit |
| chemical formula | Be 3 Al 2 Si 6 O 18 + Mn |
|
Mineral class (and possibly department) |
see beryl |
| Similar minerals | Aquamarine , beryl , golden beryl , Goshenite , heliodor , morganite , emerald |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | dihexagonal-dipyramidal; 6 / m 2 / m 2 / m |
| Physical Properties | |
| Mohs hardness | 7.5 to 8 |
| Density (g / cm 3 ) | 2.65 to 2.75 |
| Cleavage | indistinct |
| Break ; Tenacity | uneven to scalloped |
| colour | orange-red to red to purple-red |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss to matt |
| Other properties | |
| Chemical behavior | is not attacked by acids, not even by HF |
Red beryl , also known as bixbit or red emerald , is a rare red variety of the mineral beryl . Its intense red color is caused by the addition of manganese or lithium .
Etymology and history
Bixbit was the original name given by Alfred Eppler in 1912 for the red beryl discovered by Maynard Bixby (1853–1935). However, this first name is rejected by the CIBJO due to the risk of confusion with the mineral bixbyite, also named after Bixby, and should no longer be used.
Maynard Bixby, an American prospector and claim owner , discovered small, opaque and intensely red beryl crystals for the first time in 1897 in "Topaz Cave" (Maynard Topaz Mine) in Juab County (Utah, USA). Gem-quality red beryl was not found until 1958 in the Wah Wah Mountains in Beaver County (Utah, USA).
colour
The rare red color of red beryl is caused by Mn 2+ , which replaces the Al atom in the crystal lattice . The best color is a rich red ("stoplight") with a hint of blue. The colors vary between orange-red, pink, red-violet and dark red, with many nuances.
Education and Locations
In the late Cretaceous period (100 - 65 mya ) the younger parts of the Rocky Mountains emerged , with deep cracks in the earth's crust . In the course of volcanic activity (approx. 20 mya) what is now Utah was covered by five or more layers of topaz- containing rhyolite . Later, hot, fluorine-containing gases or vapors rose from the depths and found their way up through shrinkage cracks in the cooled rhyolite rock. They encountered groundwater close to the surface of the earth, which evaporated and left small cavities. Remaining water vapor could react with the mineral-rich gases at high temperatures (300 to 650 ° C) and low pressure, which allowed red beryl crystals to grow.
The red beryl is found in cavities and crevices of the volcanic rock rhyolite . The minerals bixbyite , hematite , orthoclase , pseudobrookite , quartz , spessartine ( garnet ) and topaz are associated with it .
Very rare, cut-worthy crystals can only be found in a few places in the west and southwest of the USA :
- "Violet Claims" in the Wah Wah Mountains ( Beaver County ) in southern central Utah, with noble, raspberry-red crystals in white rhyolite. This site is well known for its large, clear crystals. As with all private claims (leased find area), collecting is only permitted with the leaseholder's permission. The crystals are found in cracks in the rhyolite in a narrow area of only 900 × 1900 m.
- " Thomas Range " in the western Utah desert (near Wildhorse Springs , 65 km northwest of Delta in Millard County ). There is red beryl as clear, dark red to light pink, raspberry-colored crystals in light gray rhyolite. This place is both a classic ( type locality ) and popular site for collectors interested in mineralogy. It is also known worldwide for its topaz crystals . The "Thomas Range" area, especially the " Topaz Mountain ", was discovered in 1859 by Henry Engelmann. The "Topaz Mountain" is visited annually by thousands of collectors who look for topaz and other rare minerals here.
- Paramount Canyon and Round Mountain in "Taylor Creek Tin District" in the Black Range in Sierra County in New Mexico , where smaller crystals in white rhyolite place.
Use as a gem stone
Red beryl is almost exclusively processed into gemstones , but due to its rarity it is often replaced by irradiated or fired beryl varieties or syntheses .
Red beryl is the rarest beryl. Most faceted stones weigh less than 1 carat and have more or less inclusions up to the opaque “ bubble gum ” quality. However, "Bubble Gum" is also used as the color name for pink, regardless of the purity. The largest crystal to date was 1.4 × 3.4 cm and weighed 54 ct. The largest faceted red beryl (not pure) weighs 8 ct. The usual size of good, faceted stones is only 0.15 ct.
Faceted, pure stones with the coveted "stoplight" red are very much in demand. If they weigh more than 1 ct, they are extremely rare and have a corresponding price.
According to the Geological Survey of Utah , red beryl is said to be so rare that only about one red beryl is mined for every 150,000 gem quality diamonds.
Differentiation from Pezzottait
In 2002 a pink mineral was found in Madagascar , which was initially thought to be a less valuable variety of "red beryl" and was called pezzottaite . Since 2003, however, pezzottaite has been recognized as an independent mineral that is related to the other minerals of the beryl group, but its structure differs so much from them that it is not isostructural with them.
Red beryl has hexagonal crystals with 6 equal sides bordered by flat ends. Pezzottaite has trigonal crystals with pyramid-like end faces. Pezzottaite crystals are usually larger than red beryl crystals. The bedrock ( matrix ) of red beryl is white or gray rhyolite. Pezzotaite crystals sit on gray granite .
Red beryls are normally not eye-clean if the stone / crystal weighs more than 1/10 ct. They then usually have inclusions , internal cracks, rhyolite haze and / or black spots. Pezzottaite usually shows bubbles and / or cracks or breaks. Red beryl has a refractive index from 1.567 to 1.580, pezzotaite from 1.601 to 1.620.
See also
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. 112 .
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 220-223 .
Web links
- Mineral Atlas: Bixbit and Mineral Portrait: Red Beryl (Wiki)
- Michael RW Peters: Beryl - Red Beryl. In: Realgems.org. July 14, 2019, accessed September 12, 2019 .
Individual evidence
- ↑ Red beryl. In: atelier-garcia.de. Atelier Garcia, accessed September 12, 2019 .
- ↑ Red Beryl. In: mindat.org. Hudson Institute of Mineralogy, accessed September 12, 2019 .
- ↑ The rarest ore. The most interesting thing in a magazine. 9. Red Beryl. In: georgiynn.ru. Retrieved September 12, 2019 .
- ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2019, accessed September 12, 2019 .
- ↑ Mineral Atlas: Pezzottaite