igneous
Tumbled black stone, likely basalt or black jasper
Basalt (fine-grained plagioclase–pyroxene rock) or opaque microcrystalline silica if jasper
AI-generated identification · may be incorrectDark black, smoothly rounded and polished, with dull to subtly vitreous luster; likely hardness 5.5–7, no visible cleavage, and moderate-to-high density. The image is insufficient to distinguish basalt from black jasper or obsidian confidently.
Identified More igneous →
Explore Tumbled black stone, likely basalt or black jasper in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark black, smoothly rounded and polished, with dull to subtly vitreous luster; likely hardness 5.5–7, no visible cleavage, and moderate-to-high density. The image is insufficient to distinguish basalt from black jasper or obsidian confidently.
Formation & geological history
Basalt forms when mafic lava cools rapidly at or near Earth’s surface, commonly in volcanic regions and oceanic crust; most examples are Cenozoic to modern, though basalt occurs throughout geologic time. Jasper forms from silica-rich sediment or hydrothermal replacement.
Uses & applications
Commonly sold as tumbled landscaping, craft, meditation, or collection stones; basalt is also used as aggregate and dimension stone, while jasper may be used in cabochons and decorative objects.
Geological facts
A magnet, streak, and hardness test can help: basalt may contain magnetic iron minerals and usually leaves a gray streak, whereas jasper can scratch glass and has a white streak. Obsidian is another possibility if the surface is glassy and conchoidally fractured.
Field identification & locations
Common sources include volcanic terrains worldwide, especially Hawaii, Iceland, India, Mexico, and the Pacific Northwest; black jasper is widely marketed from India and Brazil. Confirm identity by testing hardness, streak, density, and magnetism.
