Black Obsidian
Volcanic Glass (Obsidian) · Decorative Stone / Mineral Specimen
Crystal System
Amorphous (Non-crystalline)
Mineral Group
Mineraloid
Chemical Formula
SiO2 (Silicon Dioxide with impurities)
Formation Process
Igneous, formed from rapidly cooling felsic lava where chemical constituents do not have time to form a crystalline structure.
About This Crystal
An opaque, pitch-black rock displaying a glossy, vitreous luster and prominent conchoidal fracture surfaces.
Physical Characteristics
Color is deep black with a vitreous to greasy luster; streak is white; no cleavage; fractures conchoidally with sharp edges; specific gravity is approximately 2.35 to 2.45.
Optical Properties
Isotropic due to its amorphous structure, displaying no birefringence or pleochroism.
Hardness & Durability
Origin Region
Found globally in areas with volcanic activity including the USA, Mexico, Iceland, Italy, and Japan.
Hardness & Durability
Mohs hardness of 5 to 5.5; brittle with sharp edges; sensitive to heavy impacts but stable under normal environmental conditions.
Care & Maintenance
Clean with warm soapy water and a soft cloth; store separately from harder gems to avoid scratching other stones; avoid harsh chemicals.
Rarity & Value
Common; widely accessible and affordable, primarily valued for decorative carvings, lapidary art, and holistic uses.
Special Characteristics
Displays extremely sharp conchoidal fractures historically used for making cutting tools and arrowheads.
Lore & History
Historically used by ancient civilizations for tools, weapons, and mirrors. In modern metaphysical practices, it is regarded as a stone of grounding, protection, and emotional release.