Realgar
Species
Uncommon · As₄S₄
Arsenic sulfide of low-temperature hydrothermal veins, also deposited by hot springs and volcanic vents. Long exposure to light crumbles it to a yellow powder of pararealgar or of arsenolite and orpiment. Both realgar and orpiment are toxic and need careful handling.
Identity
- Formula
- As₄S₄
- Chemical class
- Sulfide
- Also known as
- Ruby sulfur, Ruby of arsenic
Crystallography
- Crystal system
- Monoclinic
- Habits
- Prismatic, Massive, Granular
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 1.5
- Density
- 3.56 g/cm³
- Luster
- Resinous, greasy
- Colors
- red, orange-red, orange
- Streak
- red-orange to red
- Transparency
- Transparent, Translucent
Geology
- Origins
- Hydrothermal, Volcanic, Sedimentary
- Host rocks
- Volcanic rock, Limestone and chalk
- Associated minerals
- Orpiment, Stibnite, Calcite, Pyrite
- Geography
- Romania, China, USA (Nevada), Switzerland, North Macedonia
Classification
- Rarity
- Uncommon
- Gem quality
- No
Arcane properties
- Affinity
- Fire, Death
- Effects
- Elemental fire, Warding
- Planar origin
- Material Plane
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Realgar. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Realgar: Mineral information, data and localities. mindat.org.
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