Blue Obsidian
Volcanic glass (SiO2-rich); natural or manufactured
Blue-colored volcanic glass; genuine natural blue obsidian is very rare, while much blue obsidian on the market is manufactured glass.
- Mohs hardness
- 5-5.5
- Color
- Translucent blue, sky to deep blue
- Type
- crystal
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Overview
Blue obsidian is obsidian (volcanic glass) showing a blue color, ranging from pale sky blue to rich translucent azure. Genuine natural blue obsidian is extremely rare; most brightly colored blue "obsidian" sold commercially is in fact manufactured glass or treated material.
Natural obsidian gets faint color from trace elements and tiny inclusions, but vivid, uniform blue is a strong sign of a man-made or dyed product. True natural blue obsidian, where it exists, owes its tint to trace iron and microscopic inclusions and is usually subtle and somewhat smoky.
Because of widespread imitation, buyers should be cautious and seek reputable sources.
Formation & geology
Where genuinely natural, blue obsidian forms like all obsidian — by the rapid quenching of silica-rich rhyolitic lava into glass with no time to crystallize. A faint bluish or blue-gray tint can arise from trace iron, titanium, or finely dispersed inclusions that scatter light.
Truly vivid natural blue is rare and reported only from a few volcanic localities. Some material attributed to places such as Mexico, Armenia, or the western USA shows subtle natural blue tones.
Most intensely blue "obsidian" on the market is slag glass or laboratory-made glass colored with cobalt or copper compounds, not a natural volcanic rock at all.
How to identify it
Be skeptical of bright, even, transparent blue. Natural obsidian is typically dark and only subtly tinted; a strong, glassy, uniformly colored blue often indicates manufactured glass.
Genuine obsidian is glassy, breaks with conchoidal fracture, has hardness 5-5.5, and may contain natural flow lines, bubbles, or tiny crystallites. Man-made glass tends to be flawlessly clear, may show swirl marks or perfectly round bubbles, and lacks natural inclusions.
Look-alikes and fakes: cobalt or copper glass, dyed or coated stones, and slag glass all mimic blue obsidian. Reliable distinction may require gemological testing; provenance from a trusted dealer is the most practical safeguard.
Uses & significance
Blue obsidian (natural or manufactured) is used for beads, cabochons, pendants, spheres, and decorative carvings, valued for its attractive translucent color and glassy polish.
Manufactured blue glass is inexpensive and abundant in the crystal and craft trade; genuine natural blue obsidian, being rare, is more of a collector's curiosity.
In metaphysical circles blue obsidian is associated with communication, calm, and clarity, though these claims are spiritual rather than scientific. Buyers seeking natural material should ask whether a piece is natural volcanic glass or man-made before purchase.
Frequently asked questions
Is blue obsidian natural?
Genuine natural blue obsidian is very rare; most vivid blue obsidian sold is manufactured or dyed glass, not natural volcanic rock.
How can I tell real blue obsidian from fake?
Natural obsidian is usually dark and subtly tinted with natural inclusions, while man-made glass is flawlessly clear with swirls or perfect bubbles.
What gives blue obsidian its color?
Faint natural blue can come from trace iron and inclusions, but bright blue usually comes from added colorants like cobalt or copper in glass.
How hard is blue obsidian?
Like other obsidian and glass it has a hardness around 5 to 5.5 and breaks with sharp conchoidal fracture.
Blue Obsidian guides
In-depth guides for identifying, valuing, and understanding Blue Obsidian.
