mineral

Polished tektite (likely indochinite)

Natural silica-rich impact glass; mainly SiO₂ with Al₂O₃, FeO, MgO, CaO, and Na₂O

AI-generated identification · may be incorrect

Black to dark olive-brown, vitreous-to-waxy luster, amorphous glass rather than crystalline structure; Mohs hardness about 5.5–6.5, conchoidal fracture, specific gravity roughly 2.3–2.5. The elongated, irregular form and flow-like surface are consistent with a polished tektite.

Identified September 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed about 0.79 million years ago when the Australasian impact melted and ejected terrestrial sediments, rapidly quenching them into glass. Commonly associated with Southeast Asian strewn-field deposits.

Uses & applications

Used as a collector specimen, lapidary material, pendant, and cabochon; it has little industrial value.

Geological facts

Tektites are impact glasses, not volcanic obsidian; surface textures may preserve aerodynamic ablation or sculpted flow features. Exact identification requires locality, density, and laboratory testing because black glass and slag can look similar.

Field identification & locations

Commonly found in Thailand, Vietnam, Laos, Cambodia, southern China, and Australia. Field clues include low density, glassy fracture, lack of bubbles or crystals, and a natural sculpted shape; polishing obscures diagnostic surfaces.