mineral
Possible tektite or volcanic glass specimen
Natural silica glass; composition commonly near SiO₂, but exact identification requires chemical testing
AI-generated identification · may be incorrectBlack to dark brown, vitreous-to-resinous luster, strongly convoluted or fluted surface, and no visible crystal structure; hardness is typically about 5–6 Mohs. The elongated shape and glossy, flow-like texture may also resemble industrial slag, so visual identification is uncertain.
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Physical properties
Black to dark brown, vitreous-to-resinous luster, strongly convoluted or fluted surface, and no visible crystal structure; hardness is typically about 5–6 Mohs. The elongated shape and glossy, flow-like texture may also resemble industrial slag, so visual identification is uncertain.
Formation & geological history
If genuine, it may be a tektite formed by meteorite-impact melting, or volcanic glass such as obsidian formed by rapid cooling of silica-rich lava; age depends on locality. The pictured surface could alternatively be weathered anthropogenic slag.
Uses & applications
Tektites and obsidian are mainly collector specimens; obsidian is used for ornaments, tools, and occasionally jewelry. Slag has little geological or commercial value.
Geological facts
Tektites commonly show aerodynamic forms and sculpted ablation surfaces, while obsidian usually has conchoidal fracture and a more uniformly glassy texture.
Field identification & locations
Check for conchoidal fracture, low density, bubbles, magnetic response, and a fresh unweathered surface; laboratory XRF, specific gravity, and microscopy are needed to distinguish tektite, obsidian, and slag. Common tektite localities include Southeast Asia, Australia, and North America.
