Golden beryl
The golden beryl is a light yellow to greenish yellow ( Heliodor ) variety of the mineral beryl (Be 3 Al 2 [Si 6 O 18 ]). Its chemical and physical properties are the same as those of the other beryl varieties. In contrast to the emerald , however, it rarely has inclusions.
colour
The yellow color of the golden beryl arises when the aluminum, which has an octahedral structure in the chemical formula , is replaced by Fe 3+ . In nature, however, it can also be generated or amplified by the emission of alpha, beta and gamma radiation from neighboring radioactive minerals such as zircon , columbite , uraninite or others. Due to the radiation, Fe 2+ ionizes to Fe 3+ , the previously blue color gradually changing from greenish-blue to yellow.
Locations and discovery
Golden beryl is mostly found in the same gemstone deposits as aquamarine . The most important sites are Sri Lanka and South West Africa .
Gold beryl was probably found for the first time in 1912 in the Rössing mine in what was then German South West Africa (now Namibia ). The magazine Die Woche wrote in 1913 about the "new German gemstone Heliodor":
"German South West Africa, our colony so often wrongly reviled and to which we owe quite substantial diamond finds, has given the world a new gemstone, the 'Heliodor', whose discovery we actually owe to chance."
The stone was brought to the gemstone cutting center in Idar-Oberstein , where the jeweler and mineralogist Wilhelm Lucas von Cranach examined it and gave it the name Heliodor. According to Cranach, it was actually a hitherto unknown stone that, despite its gold color, should not be confused with golden beryl. He wrongly attributed the color of the golden beryl to chromium oxide and that of the heliodore to iron oxide. Kaiser Wilhelm II liked the stone so much that he compared it to "the color of beautiful old Moselle wine".
Use as a gem stone
Like the other noble beryls, golden beryl or heliodor are processed into gemstones and are mostly given a facet cut . In order to meet the need for strong golden yellow stones, pale yellow rough stones are reinforced with the help of artificially generated ionizing radiation .
However, its sensitivity to heat places high demands on processing - at a temperature of 250 ° C or more, discoloration occurs, so that the beryl turns pale.
literature
- Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th, revised and expanded edition. BLV Verlags GmbH, Munich et al. 2002, ISBN 3-405-16332-3 , p. 112 .
- Bernhard Bruder: Beautified stones . Neue Erde, Saarbrücken 1998, ISBN 3-89060-025-5 , p. 53, 54 .
Web links
Individual evidence
- ↑ Die Woche, No. 19, of May 10, 1913, p. 772