Black Obsidian with White Banding
Natural Volcanic Glass var. Banded Obsidian · Decorative Stone and Semi-Precious Gemstone
Crystal System
Amorphous (Non-crystalline)
Mineral Group
Mineraloid
Chemical Formula
SiO2 (predominantly silica, amorphous volcanic glass with iron and magnesium oxides causing dark coloration)
Formation Process
Igneous (Extrusive); forms when felsic lava extruded from a volcano cools rapidly without sufficient time for crystal growth.
About This Crystal
A tumbled, smooth specimen displaying a striking contrast between an opaque, glossy jet-black upper section filled with minute gas bubbles or micro-crystallites, and a grayish-white band cutting across the lower portion. It has a high vitreous to greasy luster with an irregular, polished, bulbous shape.
Physical Characteristics
Color ranges from deep black to translucent gray-white; white streak; no cleavage due to amorphous nature; breaks with a sharp, distinct conchoidal fracture; specific gravity around 2.35 to 2.60; brittle tenacity; non-magnetic.
Optical Properties
Singly refractive (isotropic due to lack of a crystal lattice); refractive index is approximately 1.48 to 1.51; exhibits no pleochroism or birefringence.
Hardness & Durability
Origin Region
United States (Oregon, California), Mexico, Iceland, Italy, Japan, and areas with recent volcanic activity
Hardness & Durability
Mohs hardness of 5 to 5.5; fair to poor toughness because it breaks easily along conchoidal fracture planes; sensitive to sharp impacts; moderate wearability for jewelry if protected in settings.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic or steam cleaners; store separately in a fabric-pouch to prevent scratching softer stones or being scratched by quartz-hard minerals; stable in light and heat.
Rarity & Value
Common; relatively inexpensive and widely available; value is determined by unique patterns, chatoyancy (in sheen obsidian), or size, with common price ranges from low to moderate.
Special Characteristics
Features distinct color zoning and natural contrasting banding between black glass and micro-crystalline white inclusions, often called snowflake or banded patterns depending on the crystallization degree.
Lore & History
Historically used by ancient Mesoamerican civilizations (such as the Aztecs and Mayans) to carve sharp tools, weapons, and ritual mirrors. In modern metaphysical practices, it is traditionally associated with the root chakra, grounding energy, and serving as a psychic shield for protection and emotional clarity.