igneous
Small black stone fragment (possibly obsidian)
Unidentified dark rock; obsidian is volcanic glass (composition typically rhyolitic)
AI-generated identification · may be incorrectThe fragment appears black, glossy, and irregular, but its small size and the photo do not reveal diagnostic texture. If obsidian, hardness is about 5–5.5 Mohs, with a glassy luster and conchoidal fracture; crystal structure is absent.
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Physical properties
The fragment appears black, glossy, and irregular, but its small size and the photo do not reveal diagnostic texture. If obsidian, hardness is about 5–5.5 Mohs, with a glassy luster and conchoidal fracture; crystal structure is absent.
Formation & geological history
If obsidian, it formed when silica-rich lava cooled rapidly, commonly in volcanic settings; its age cannot be determined from the image.
Uses & applications
Could be a decorative or collected fragment; obsidian is also used for jewelry and historically for very sharp cutting tools.
Geological facts
Obsidian is natural volcanic glass, unlike man-made glass, and often breaks with curved, razor-sharp edges.
Field identification & locations
A glassy surface and curved fracture may support obsidian identification, but other black minerals or manufactured material can look similar. A closer view and simple tests are needed; obsidian occurs near volcanic regions worldwide.
