Mineralpedia Details for Realgar

Named for the Arabic rahj al ghar, meaning “powder of the mine,” likely in allusion to its sometimes powdery form. Relatively common, fine crystals come from localities including, Germany, Switzerland, Romania, the Czech Republic, Macedonia, Russia, Japan, China, and the USA. Realgar commonly occurs in hydrothermal veins of low temperature usually associates with other arsenic minerals or antimony minerals. It can also occur as a volcanic sublimation as well as in hot springs and can also be found in carbonate and clay sedimentary deposits. Upon exposure to light for long periods, Realgar will disintegrate to a powder.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/realgar.pdf

Formula

AsS 

Crystal System

Monoclinic 

Crystal Habit

Prismatic, Massive - Granular, Druse 

Cleavage

Good, None, None 

Luster

Sub Metallic 

Color

aurora red, orange yellow, dark red 

Streak

orange 

Class

Monoclinic - Prismatic 

Fracture

Sectile 

Hardness

1.5-2 

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Mindat

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Acicular Realgar spray to 3mm tucked and well protected in a large vug associated with snow white sprays of Picropharmacolite. This is a hard to obtain combination for this mine. Also bright red acicular crystals covering yellow 1 to 1.5cm Orpiment crystals.

Bright red prismatic crystals of Realgar to 2mm.

Acicular ed needles to 3mm in Colemanite matrix.

Realgar was rare at Langban having been found in scare quantities. In the book "Langban" et al by Bollmark et al, they explain it occured in two different paragenesis one in magnetite and the other granular Hematite. This specimen is the granular Hematite, which according to the book was found in 1937 by EG Varg. The specimen is very rich with corroded crystals to 2mm. There is an unidentified acicular crystal which occurs in bundles within the vugs.

Two cherry red parallel growth crytsals to 3mm in vug.

Deep, bright red prismatic crystals to 5mm in vugs.