Likely basalt fragments

Dark gray, fine-grained, dull to weakly vitreous, with no obvious cleavage; Mohs hardness about 6, specific gravity roughly 2.8–3.0. The left piece appears sawn or broken into a block, while the right is naturally rough and weathered.

Basalt is an extrusive igneous rock formed when iron- and magnesium-rich lava cools rapidly at or near Earth’s surface, commonly in volcanic fields and oceanic crust. Individual specimens may range from recent lava to Precambrian material, so age cannot be determined from the image.

Used extensively as crushed aggregate, road stone, railroad ballast, building stone, and basalt fiber; attractive fine-grained pieces may be collected but are rarely used as gemstones.

Basalt is Earth’s most abundant volcanic rock and forms much of the ocean floor. It commonly develops vesicles, but neither visible specimen shows clear vesicles.

Identify it by its dark color, heavy feel, fine texture, and resistance to scratching with a steel blade; it commonly occurs in volcanic regions, including Hawaii, Iceland, India, and the Columbia River area. A laboratory test or fresh broken surface would be needed to distinguish it confidently from fine-grained gabbro or other dark rocks.