igneous
Possible basalt or iron-rich slag
Basalt (tentative; identification uncertain from image)
AI-generated identification · may be incorrectDark black, fine-grained, rounded, and weakly lustrous with scattered pale inclusions; likely hardness about 5–6 and massive texture. The smooth surface may reflect water-wear or polishing, while metallic-looking patches could indicate iron minerals or industrial slag.
Identified More igneous →
Explore Possible basalt or iron-rich slag in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark black, fine-grained, rounded, and weakly lustrous with scattered pale inclusions; likely hardness about 5–6 and massive texture. The smooth surface may reflect water-wear or polishing, while metallic-looking patches could indicate iron minerals or industrial slag.
Formation & geological history
If basalt, it is a volcanic mafic rock formed from rapidly cooled lava, commonly ranging from Precambrian to modern age. Its rounded form suggests stream, beach, or glacial transport; slag is human-made and not technically rock.
Uses & applications
Basalt is used as crushed aggregate, road stone, rail ballast, and occasionally decorative material. A common pebble has negligible commercial value.
Geological facts
The image alone cannot reliably distinguish basalt from magnetite-rich rock, coal-like material, or black furnace slag. A magnet, streak test, and fresh broken surface would greatly improve identification.
Field identification & locations
Basalt is common in volcanic regions and river gravels worldwide; it is typically nonvesicular, dense, and leaves a gray-black streak. Strong magnetism, glassy texture, bubbles, or flow-like swirls would favor slag or an iron-rich specimen.
