Yellow-Green Obsidian
Silica glass (~70-75% SiO2), colored variety
A chartreuse yellow-green glass sold as obsidian; the bright color is manufactured and does not occur in natural volcanic glass.
- Mohs hardness
- 5-6
- Color
- Yellow-green to chartreuse, translucent
- Type
- igneous
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Overview
Yellow-Green Obsidian is a chartreuse glass in the colored-obsidian range. Natural obsidian is not produced in a bright yellow-green; this color is a hallmark of manufactured glass.
The material is made by melting silica with colorants such as chromium, iron, or, in some pieces, uranium (which yields the classic glowing "uranium glass" yellow-green). It may also be sold as obsidianite or art glass.
It is an inexpensive decorative product valued for its unusual color and, in uranium-glass pieces, for its fluorescence under UV light.
Formation & geology
Authentic obsidian forms when viscous rhyolitic lava cools too quickly to crystallize, producing a glass tinted only by natural iron and inclusions.
Yellow-green material is engineered: a silica melt receives chromium, iron, or uranium compounds before being cooled to a glass. Uranium-doped versions fluoresce bright green under ultraviolet light, an unmistakable sign of manufactured glass rather than volcanic origin.
How to identify it
Color: Yellow-green to chartreuse, often translucent.
Luster: Vitreous; conchoidal fracture.
Hardness: ~5-6.
Streak: White.
UV test: Uranium-glass pieces glow bright green under UV, a dead giveaway that the material is manufactured glass.
Look-alikes: Peridot and prehnite are natural and stony; peridot is harder (6.5-7) with crystal form. Yellow-green obsidian is glass, showing bubbles, swirls, and even color.
Uses & significance
Yellow-Green Obsidian is used for tumbles, beads, spheres, and pendants in budget jewelry and crystal displays. Uranium-glass examples are collected as novelties for their UV fluorescence.
Metaphysical sellers connect it to energy and the solar plexus, claims based on folklore. As manufactured glass it has decorative value only. Uranium-glass pieces are weakly radioactive but generally considered safe to handle.
Frequently asked questions
Is yellow-green obsidian natural?
No. The bright chartreuse color is manufactured; natural obsidian does not form this color.
Why does some of it glow under UV?
Those pieces are uranium glass, doped with uranium, which fluoresces bright green and confirms a manufactured origin.
Is uranium glass dangerous?
It is only very weakly radioactive and is generally considered safe to handle and display.
Could it be peridot?
No. Peridot is a harder natural crystal; this is soft colored glass with bubbles.
Yellow-Green Obsidian guides
In-depth guides for identifying, valuing, and understanding Yellow-Green Obsidian.
Yellow-Green Obsidian identified by the community
Real specimens identified with Rock Identifier.
