metamorphic
Banded metamorphic rock, likely gneiss
Gneiss (probable; mineral composition cannot be confirmed from the image)
AI-generated identification · may be incorrectGray-brown with distinct wavy, parallel light and dark bands and a coarse-looking texture. Typical gneiss is composed mainly of quartz, feldspar, and mica; hardness is about 6–7 Mohs, with a nonmetallic luster and no consistent cleavage as a whole rock.
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Physical properties
Gray-brown with distinct wavy, parallel light and dark bands and a coarse-looking texture. Typical gneiss is composed mainly of quartz, feldspar, and mica; hardness is about 6–7 Mohs, with a nonmetallic luster and no consistent cleavage as a whole rock.
Formation & geological history
Forms when existing rock is recrystallized and segregated into bands under high heat and pressure, commonly deep in continental crust; specimens may be Precambrian or younger.
Uses & applications
Gneiss is used as dimension stone, paving, aggregate, and landscaping stone; this small piece is mainly suitable for collecting or display.
Geological facts
The alternating mineral bands are called gneissic foliation and can resemble stripes or folded ribbons.
Field identification & locations
Look for coarse, interlocking grains and compositional bands; the image does not show enough detail to distinguish gneiss confidently from other foliated rocks. Gneiss occurs widely in ancient continental shields and mountain belts.
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