sedimentary

Likely black beach pebble

Undetermined; possibly basalt, chert, or dark slate

AI-generated identification · may be incorrect

Small, smooth, rounded, dark gray-black specimen with a dull to faintly waxy luster; hardness and specific gravity cannot be determined reliably from the image. The shape suggests water abrasion, and no visible crystals or cleavage are apparent.

Identified August 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Most likely a naturally rounded pebble formed by erosion and transport in a beach, river, or gravel deposit. Geological age and exact formation process require testing or a closer image.

Uses & applications

Primarily a curiosity or inexpensive collecting specimen; if basalt, similar material is used as aggregate and building stone, while chert may be used for tools and decorative objects. Estimated value is usually $1-$10.

Geological facts

The smooth teardrop-like form may also indicate a tumbled stone, potentially artificially polished. A streak test, hardness test, and close inspection of texture would distinguish basalt from chert, slate, or industrial slag.

Field identification & locations

Look for tiny interlocking crystals and a heavy, fine-grained texture for basalt; a glassy/waxy surface and conchoidal fracture suggest chert. Common sources include beaches, riverbeds, and landscaping gravel; avoid destructive testing if provenance matters.