Smoky Obsidian
Volcanic glass (silica-rich, ~70-75% SiO2, amorphous)
Translucent smoky-gray obsidian that transmits a hazy light, intermediate between clear and fully black volcanic glass.
- Mohs hardness
- 5-5.5
- Color
- Smoky gray-brown, translucent to nearly black
- Type
- igneous
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Overview
Smoky Obsidian is a trade name for translucent obsidian with a smoky gray-to-brownish tone, much like the look of smoky quartz but in glass form. Held to light, it glows with a hazy, smoke-like transparency.
The stone is natural volcanic glass whose smoky appearance comes from a moderate amount of fine inclusions and dissolved iron that partially absorb and scatter light, more than clear obsidian but less than fully black obsidian.
It is a common, affordable ornamental material and a frequent host for sheen and snowflake patterns.
Formation & geology
Smoky Obsidian forms by the rapid cooling of silica-rich lava into an amorphous glass. Its smoky color reflects an intermediate concentration of light-scattering microbubbles, nanoscale inclusions, and dissolved iron within the glass.
Where these features are sparse the glass is clear; where dense it is black; the smoky variety lies between. The exact tone depends on the lava's chemistry and how many impurities and bubbles were trapped during quenching. It occurs at the margins of rhyolitic flows and domes alongside other obsidian types.
How to identify it
Confirm obsidian: conchoidal fracture, vitreous luster, hardness ~5-5.5, white streak. Smoky Obsidian is translucent smoky gray-brown, transmitting hazy light at the edges and darkening toward black in thicker pieces.
Look for the smooth glassy surface, sharp edges, and absence of crystal faces.
Look-alikes: smoky quartz (crystalline, hardness 7, with crystal faces and greater transparency), gray chalcedony (waxy, harder), and smoky glass objects. Its glassy fracture and lower hardness distinguish it from quartz.
Uses & significance
Smoky Obsidian is cut into tumbled stones, cabochons, beads, spheres, and carvings, and often hosts sheen or snowflake patterning. It is an inexpensive and widely available lapidary material.
Like all obsidian it knaps into very sharp edges, used historically for tools and blades.
Metaphysically it is associated with grounding, protection, and releasing negativity, claims that are spiritual rather than scientifically established.
Frequently asked questions
Is Smoky Obsidian the same as smoky quartz?
No. Smoky quartz is crystalline quartz (hardness 7) colored by natural radiation, while smoky obsidian is amorphous volcanic glass (hardness ~5-5.5) with conchoidal fracture.
Why is Smoky Obsidian translucent?
It contains a moderate amount of inclusions and dissolved iron, more than clear obsidian but less than black, so it transmits hazy, smoke-like light.
Is Smoky Obsidian natural?
Yes, smoky gray-brown translucency is a common natural appearance for obsidian, intermediate between clear and black.
How is it different from gray obsidian?
The two overlap; smoky obsidian emphasizes a translucent, smoke-like brown-gray glow, while gray obsidian may be a flatter, more neutral gray.
Smoky Obsidian guides
In-depth guides for identifying, valuing, and understanding Smoky Obsidian.
