Black Obsidian with Sheen
Volcanic Glass var. Sheen Obsidian · Semi-Precious Gemstone and Decorative Stone
Crystal System
Amorphous (Non-crystalline)
Mineral Group
Mineraloid
Chemical Formula
SiO2 with minor impurities (Fe, Mg)
Formation Process
Extrusive igneous process formed by the rapid cooling of silica-rich felsic lava without sufficient time for crystal growth
About This Crystal
An opaque, smooth, tumbled stone with a deep black body color displaying subtle silvery-white fibrous reflections or chatoyancy across the surface, exhibiting a glassy to vitreous luster
Physical Characteristics
Black to dark brown body color with a white streak, completely lacks cleavage, exhibits sharp conchoidal fracture, specific gravity around 2.35 to 2.45, and brittle tenacity
Optical Properties
Singly refractive (isotropic), vitreous luster, displays a silvery sheen or chatoyancy caused by microscopic gas bubbles or aligned mineral nanocrystals trapped during cooling
Hardness & Durability
Origin Region
Found globally near active or recent volcanic areas, including USA (Oregon), Mexico, Iceland, and Japan
Hardness & Durability
Mohs hardness of 5 to 5.5, moderate durability, sensitive to scratching by harder materials and sharp impacts due to conchoidal fracture
Care & Maintenance
Clean with warm soapy water and a soft cloth, avoid ultrasonic cleaners and harsh chemical solvents, store separately to prevent scratching other stones
Rarity & Value
Common, widely accessible and affordable, with value determined by the quality and intensity of the optical sheen or chatoyancy
Special Characteristics
Features a distinct silvery sheen or chatoyant effect caused by light reflection off microscopic mineral inclusions oriented during rapid volcanic cooling
Lore & History
Historically used by ancient civilizations like the Aztecs and Mesoamericans for making tools, mirrors, and weapons. In modern metaphysical practices, it is traditionally associated with grounding, protection, and the root chakra, though these are cultural beliefs rather than scientific claims.