Black Obsidian
Volcanic Glass (Obsidian) · Decorative Stone / Mineral Specimen
Crystal System
Amorphous (Non-crystalline)
Mineral Group
Mineraloid
Chemical Formula
SiO2 with varying amounts of Fe and Mg
Formation Process
Extrusive igneous rock formed from rapidly cooled felsic lava
About This Crystal
A polished dark black sphere displaying a smooth, highly reflective vitreous luster and complete opacity under normal lighting conditions.
Physical Characteristics
Black body color, white streak, conchoidal fracture with extremely sharp edges, specific gravity of approximately 2.35 to 2.60, brittle tenacity, lacks cleavage.
Optical Properties
Singly refractive, amorphous nature results in isotropic optical behavior with no birefringence.
Hardness & Durability
Origin Region
United States, Mexico, Iceland, Italy, Japan
Hardness & Durability
Mohs hardness of 5 to 5.5, brittle toughness, sensitive to sharp impacts, moderate wearability for jewelry if protected.
Care & Maintenance
Clean with warm soapy water and a soft cloth, avoid harsh chemicals, ultrasonic cleaners, and prolonged direct sunlight.
Rarity & Value
Common, widely accessible worldwide with value determined primarily by carving quality, size, and finish.
Special Characteristics
Can sometimes exhibit sheens like golden or silver obsidian, or snowflake patterns due to cristobalite inclusions, though this specific piece is jet black.
Lore & History
Historically used by ancient Mesoamerican cultures to make tools, weapons, and scrying mirrors. Often associated in metaphysical lore with grounding, protection, and the Root Chakra.