Quick Facts
Formation & Origin
Realgar forms in low-temperature hydrothermal veins, hot spring deposits, and as a volcanic sublimate. It often occurs alongside its yellow cousin orpiment (As₂S₃), with which it shares many geological environments. Both are arsenic sulfide minerals.
Fine crystals from China's Hunan Province reach several centimeters and display a stunning crimson color with resinous to adamantine luster. These form in hydrothermal veins within carbonate host rocks where arsenic-rich fluids deposited their mineral load as temperatures dropped.
Realgar is light-sensitive. Prolonged exposure to sunlight causes it to slowly decompose into paraealgar, a yellow powdery mineral, through a light-induced structural rearrangement. Museum specimens must be stored in darkness to preserve their vivid red color. This instability is why ancient realgar pigments in artwork have often turned yellow or orange over centuries.
Identification Guide
Realgar is identified by its vivid crimson-red color, very low hardness (1.5, easily scratched), and orange-red streak. The resinous luster and monoclinic crystal habit (short prismatic crystals) are additional features.
Distinguish from cinnabar (higher SG, trigonal, red streak), crocoite (lead chromate, different streak), and red glass. Realgar's extreme softness and light sensitivity are key identifiers. SAFETY NOTE: Realgar contains arsenic. Wash hands after handling and don't store with other minerals.
Spotting Fakes
Realgar is not commonly faked because it's a niche collector mineral. The main concern is degradation: specimens exposed to light may have partially converted to yellow paraealgar. Check that the red color is vivid and unaltered. Brown, yellow, or powdery surfaces indicate light damage. Well-preserved specimens with intact red crystals command premium prices. Always ask about storage history.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
In Chinese alchemy, realgar was considered a powerful protective substance used during the Dragon Boat Festival to ward off evil spirits and illness. Crystal healing practitioners approach realgar cautiously due to its arsenic content. It is considered a stone of energy, passion, and transformation. IMPORTANT: Handle with care. Do not make gem elixirs or breathe in dust. Contains arsenic.
Where It's Found
Spectacular crystal specimens
Classic European specimens
Fine crystal groups on pyrite matrix
Associated with hot springs and volcanic activity
Price Guide
Good to Know
Scratch test: At hardness 1.5, Realgar can be scratched with a fingernail. This is a display specimen, not a wearable stone.
Sources: Found in 4 notable locations worldwide, from China to United States.
Heft test: Realgar has a specific gravity of 3.56 - noticeably heavier than quartz. You'll feel the density when you pick it up.