Micaceous Orpiment from Siberia

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Description

two small leaves of Micaceous Orpiment from Siberia in plastic case

Mineral Group  sulphide
Composition  As2S3
Origin  Menkule, Yakutia, Siberia
dimension (cm)  2×1
For a long time, orpiment was mistaken for realgar, another important ore of arsenic. They often occur in close   proximity around hot water springs. Orpiment has been used for centuries in the Orient for ritual depilation. It also yields a yellow pigment that is much sought after by painters, hence its name, from the Latin auri and pigmentum, meaning “gold pigment”.

Once it was exported from the Middle East to Europe in the form of large leaves up to 10 cm long under the name ‘Turkish orpiment’. It came from Djulamerk in the land of the Kurds in south-eastern Turkey near the Iraqi border. The natural deposits of orpiment are not sufficient to meet the substantial demand for the manufacture of paints, so it is also produced artificially under the name of ‘king’s yellow’. In some deposits orpiment accompanies other arsenic ores. It forms through the weathering of these ores and covers them in a yellow crust. In cavities it forms compact, cup-shaped, lamellar, reniform to globose nodules, with a radial arrangement inside. Crystals are rare. The main deposits are at Cavnic and Baia Sprie in Romania, Allchar in Greece and, as mentioned, Djulamerk. Crystals up to 60 cm in size are found in the Minkiule deposits in Yakutskaya in eastern Siberia. Used as an arsenic ore and contains up to 61 per cent arsenic.