metamorphic
Dark, coarse-grained rock fragment (possibly amphibolite or gabbro)
Undetermined; amphibolite commonly contains hornblende and plagioclase, while gabbro contains plagioclase and pyroxene
AI-generated identification · may be incorrectSmall, dark gray specimen with a coarse, mottled texture and a rusty-brown patch; individual grains are difficult to resolve in the image. Hardness, cleavage, crystal structure, and specific gravity cannot be reliably determined visually.
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Physical properties
Small, dark gray specimen with a coarse, mottled texture and a rusty-brown patch; individual grains are difficult to resolve in the image. Hardness, cleavage, crystal structure, and specific gravity cannot be reliably determined visually.
Formation & geological history
If amphibolite, it formed when basaltic rock was metamorphosed under heat and pressure; if gabbro, it crystallized slowly from magma underground. The image does not establish its identity or age.
Uses & applications
Comparable rocks are used as crushed stone and construction aggregate; distinctive specimens may be collected or polished.
Geological facts
The brown area may be iron-oxide staining, but the photograph alone cannot confirm its composition.
Field identification & locations
The specimen is too small and visually ambiguous for a confident field identification. A fresh surface, mineral-grain examination, and hardness or magnetism tests would help distinguish likely candidates.
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