Black Obsidian
Obsidian (Volcanic Glass) · Decorative Stone / Mineral Specimen / Semi-Precious Stone
Crystal System
Amorphous (Non-crystalline); lacks an organized internal lattice structure. This specimen is carved into a figurated shape.
Mineral Group
Volcanic Glass (Silicate-rich)
Chemical Formula
SiO2 (70–75%) with MgO, Fe3O4
Formation Process
Igneous/Extrusive; forms when high-silica rhyolitic lava cools so rapidly that individual crystals do not have time to grow, resulting in a glass.
About This Crystal
An opaque, jet-black specimen with a smooth, matte to slightly waxy luster result of carving. Usually possesses a vitreous (glassy) luster when fractured. The item is carved into the likeness of a 'Sorting Hat.'
Physical Characteristics
Color: Black; Streak: White; Cleavage: None; Fracture: Conchoidal (shell-like curves); Specific Gravity: 2.35–2.6; Tenacity: Brittle; Fluorescence: Generally inert.
Optical Properties
Isotropic (singly refractive); Refractive Index: 1.450–1.550; Opaque in thick sections; non-pleochroic; no significant dispersion.
Hardness & Durability
Origin Region
Commonly sourced from Mexico, USA (Oregon, California), Iceland, and Italy (Lipari). Found in volcanic regions where silicic lava cools rapidly.
Hardness & Durability
Mohs Hardness: 5.0–5.5. Brittle and prone to chipping or scratching compared to quartz. Stable under most conditions but sensitive to sharp impacts.
Care & Maintenance
Clean with warm soapy water and a soft cloth. Avoid ultrasonic cleaners or steam cleaning due to brittleness. Store separately from harder gemstones to prevent surface scratches.
Rarity & Value
Common and abundant. Value is primarily determined by the quality of the carving, size, and presence of sheen (though none is visible here). Carvings of this size are generally affordable.
Special Characteristics
While this specimen appears matte black, Obsidian can sometimes exhibit 'sheen' or 'rainbow' effects if microscopic inclusions are present. This piece displays a classic conchoidal fracture at the base.
Lore & History
Historically used by ancient cultures (Aztecs, Mayans) for mirrors, spearheads, and ritual knives. Metaphysically, it is regarded as a stone of protection and grounding, associated with the Root Chakra and the element of Earth.