igneous
Likely quartz-bearing rock fragment
Undetermined; possibly a coarse-grained granitoid (quartz and feldspar with dark mica or amphibole)
AI-generated identification · may be incorrectThe small, blurry specimen appears mottled white and dark gray, with an irregular shape and no clearly visible crystal faces or cleavage. Hardness, luster, and crystal structure cannot be reliably determined from the image.
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Physical properties
The small, blurry specimen appears mottled white and dark gray, with an irregular shape and no clearly visible crystal faces or cleavage. Hardness, luster, and crystal structure cannot be reliably determined from the image.
Formation & geological history
If granitoid, it formed as magma cooled slowly underground; its age and exact formation environment cannot be established from this photograph. The reported coastal northeastern Brazil location makes regional crystalline-rock fragments plausible, but the image is insufficient for a firm match.
Uses & applications
A fragment this small has no obvious industrial or construction use; identified or attractive pieces may be kept as a hand specimen.
Geological facts
The dark and light patches could represent contrasting minerals, but could also reflect surface staining or shadow; a closer, well-lit image would help distinguish them.
Field identification & locations
Check for interlocking grains and test whether a corner scratches glass; these can support a quartz-rich identification but are not conclusive. Similar crystalline rocks occur in Brazil, though this specimen cannot be assigned to a specific locality.
