Cloudy Obsidian
Volcanic glass (SiO2-rich)
Obsidian with a hazy, cloud-like translucency caused by uneven distribution of tiny bubbles or incipient crystallites in the glass.
- Mohs hardness
- 5-6
- Color
- Gray to brownish-black with milky or smoky clouding
- Type
- igneous
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Overview
Cloudy Obsidian is a descriptive trade name for volcanic glass that shows soft, smoky or milky clouding rather than a uniform color. The haze comes from dense concentrations of microscopic gas bubbles or the very earliest stages of devitrification (tiny crystallites) scattering light within the glass.
When held to light, the cloudy areas appear translucent and diffuse, giving a veiled, atmospheric look. The base glass is still ordinary obsidian, amorphous and conchoidally fracturing.
It sits between fully transparent obsidian and the more structured snowflake or banded varieties, valued for its gentle, smoke-like internal patterns.
Formation & geology
Cloudy Obsidian forms from rapidly cooled rhyolitic lava in which gas bubbles or nascent crystallites are unevenly distributed. As the viscous melt freezes, trapped microbubbles or the first sub-microscopic crystals cluster in zones, producing the cloudy haze.
Very slight, partial devitrification — too little to form visible spherulites — can also create a milky scattering effect.
Like other obsidian it occurs at the chilled margins of felsic lava flows and domes in volcanic regions such as Mexico, the western United States, and Iceland.
How to identify it
Recognize it as glassy obsidian showing soft, diffuse clouds or smoky veils when backlit, instead of crisp bands or discrete spots. Luster is vitreous, fracture conchoidal, hardness 5-6, streak white.
The clouding is internal and three-dimensional, so it shifts subtly as you tilt the piece toward a light.
Distinguish from snowflake obsidian (sharp white spherulites) and banded obsidian (defined stripes). Cloudy obsidian's haze is gradational and bubble/crystallite-related, not a clean pattern. Compare also to chalcedony, which is crystalline and waxier.
Uses & significance
Cloudy Obsidian is used for cabochons, tumbled stones, and carvings where the soft internal haze adds depth. It is an inexpensive, attractive lapidary material that polishes well.
As with all obsidian, it shares the long history of tool-making thanks to its sharp fracture.
Metaphysically it is grouped with other obsidians as a grounding and protective stone, with the "cloudy" appearance sometimes tied to gentle emotional clearing; these are traditional associations rather than proven effects.
Frequently asked questions
What makes obsidian look cloudy?
Clusters of microscopic gas bubbles or the earliest tiny crystallites scatter light within the glass, producing a smoky, milky haze.
Is cloudy obsidian lower quality?
Not necessarily; the haze is a natural feature that many people find attractive. It is still genuine obsidian.
Is it the same as smoky obsidian?
The terms overlap. Both describe translucent obsidian with a smoky look; cloudy obsidian emphasizes patchy, cloud-like haze.
Can it be polished?
Yes, it polishes to a glassy shine, and the cloudiness can give finished pieces a sense of depth.
Cloudy Obsidian guides
In-depth guides for identifying, valuing, and understanding Cloudy Obsidian.
