metamorphic

Weathered metamorphic boulder, likely schist or gneiss

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface

AI-generated identification · may be incorrect

Coarse-grained, strongly weathered, rusty orange-brown and gray-blue; likely quartz and feldspar with mica or amphibole. Typical hardness is about 6–7, with weak-to-strong foliation and vitreous to dull luster.

Identified September 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when preexisting rock underwent elevated heat and pressure during regional metamorphism, commonly hundreds of millions to billions of years ago. Iron-bearing minerals oxidized during surface weathering, producing the red-brown staining.

Uses & applications

Used locally as riprap, fill, landscaping stone, and occasionally dimension stone; attractive pieces may be collected as geological specimens.

Geological facts

The image shows a natural outcrop or boulder rather than a polished specimen. Surface color is strongly affected by oxidation, lichen, and weathering, so it is not diagnostic of composition.

Field identification & locations

Common in ancient crystalline terrains and mountain belts worldwide. Look for foliation, glittering mica, visible quartz, and feldspar; a freshly broken surface and a hardness test help distinguish schist from gneiss or altered granite.