Black Obsidian
Volcanic Glass (Obsidian) · Decorative Stone / Mineral Specimen
Crystal System
Amorphous (Non-crystalline)
Mineral Group
Mineraloid
Chemical Formula
SiO2 (Silicon Dioxide with impurities like MgO and Fe3O4)
Formation Process
Igneous: Extrusive formation resulting from the rapid cooling of felsic lava without sufficient time for crystal growth
About This Crystal
Carved into the shape of a small bird perched on a branch, this specimen is a deep, solid black color with a highly polished, vitreous to sub-vitreous luster, showing smooth carved contours and a few minor natural surface imperfections.
Physical Characteristics
Color is jet black, streak is white, lacks cleavage entirely, exhibits sharp conchoidal fracture, specific gravity is approximately 2.35 to 2.45, brittle tenacity, and is non-magnetic.
Optical Properties
Isotropic (singly refractive) due to its amorphous structure, with a refractive index around 1.48 to 1.51 and opaque transparency in thick carved forms.
Hardness & Durability
Origin Region
Global; notable sources include USA (Oregon, California), Mexico, Iceland, and Italy
Hardness & Durability
Mohs hardness of 5 to 5.5, moderate toughness but brittle with extreme sharpness along fractured edges; prone to scratching by harder stones.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid harsh chemicals, ultrasonic cleaners, and protect from being scratched by harder gemstones.
Rarity & Value
Common and widely available; value depends heavily on the craftsmanship of the carving rather than the raw material itself, generally affordable.
Special Characteristics
Forms as a natural volcanic glass rather than a true mineral crystal; can sometimes exhibit sheen, snowflakes, or iridescence depending on microscopic inclusions.
Lore & History
Historically used by ancient Mesoamerican civilizations like the Aztecs for making tools, weapons, and mirrors. In modern metaphysical practices, it is traditionally associated with grounding, protection, and psychic cleansing.