Likely polished black stone or obsidian

Small, rounded, highly polished dark specimen with a black-to-gray reflective surface; obsidian has Mohs hardness about 5–5.5, glassy luster, no visible crystals, and conchoidal fracture. The image is too blurred for confident mineral identification.

Obsidian forms when silica-rich lava cools rapidly, preventing crystal growth, commonly in young volcanic flows from the Cenozoic to Recent. Similar appearance can also come from polished basalt or manufactured glass.

Used for ornamental objects, cabochons, beads, and historically sharp cutting tools; small common polished pieces have limited commercial value.

Obsidian is technically natural volcanic glass rather than a crystalline mineral. Black specimens may show gray, brown, rainbow, or snowflake patterns when viewed under strong light.

Check for natural conchoidal edges, uniform glassy texture, and absence of bubbles or perfectly manufactured surfaces; a hardness or streak test can help distinguish it from softer materials, though this photo cannot confirm the identification. Common locations include Mexico, the western United States, Armenia, Iceland, and Japan.