Stripe Obsidian
Volcanic glass (SiO2-rich) with flow banding
Obsidian crossed by parallel flow bands of differing color, formed as layers of lava with slightly different compositions froze into glass.
- Mohs hardness
- 5-6
- Color
- Black with gray, brown, or colored parallel bands
- Type
- igneous
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Overview
Stripe Obsidian, also called banded obsidian, is volcanic glass marked by parallel stripes or ribbons of contrasting color. The banding records the flow of the lava: thin layers with slightly different iron content, bubble density, or incipient crystallization froze in sequence.
Colors typically run from black through gray and brown, and the bands may be straight, wavy, or swirled, sometimes producing lace-like patterns.
It remains true obsidian — amorphous glass with conchoidal fracture — but the layered structure makes each piece visually distinctive and popular with lapidaries.
Formation & geology
Banding forms as viscous rhyolitic lava flows and shears, stretching out compositional and textural differences into thin, parallel layers. Variations in iron oxides, dissolved gas, and the degree of incipient crystallization give adjacent bands their different colors.
When the moving lava chills rapidly at a flow margin or dome, this layering is frozen into the glass as permanent stripes.
Flow-banded obsidian is common in obsidian-producing volcanic fields, including those of the western United States, Mexico, and Iceland.
How to identify it
Look for parallel or gently curving stripes of black, gray, and brown within glassy material that has vitreous luster and conchoidal fracture. Hardness is 5-6 and streak is white.
The bands are internal and continuous, often visible on both polished faces, and may show a faint sheen along the layering.
Distinguish from banded agate (crystalline chalcedony, harder, with concentric rather than flow banding) and from layered sedimentary rock (dull, not glassy). The combination of glassy fracture plus directional flow stripes confirms striped obsidian.
Uses & significance
Stripe/banded obsidian is favored for cabochons, beads, and ornamental carvings where the linear pattern can be displayed to advantage. It polishes to a high gloss.
It shares obsidian's general history as a tool and ornamental stone.
In metaphysical lore banded obsidian is described as grounding and protective, with the bands sometimes linked to balancing energies; these are folk beliefs, not scientific claims.
Frequently asked questions
What causes the stripes in obsidian?
Flow banding: as viscous lava moved, layers with slightly different iron content, gas, or crystallization were stretched out and then frozen into the glass.
Is striped obsidian the same as banded obsidian?
Yes, the names are interchangeable for obsidian showing parallel color bands.
How do I tell it from banded agate?
Agate is crystalline chalcedony, harder than obsidian, usually with concentric bands; striped obsidian is glassy with conchoidal fracture and roughly parallel flow bands.
Are the colors natural?
Yes. The stripes form naturally from compositional differences within the lava, not from dyeing.
Stripe Obsidian guides
In-depth guides for identifying, valuing, and understanding Stripe Obsidian.
