igneous
Weathered granite or granitic cobble
Granite; primarily quartz, feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse crystalline texture is obscured by weathering; mottled orange-brown surface with darker mineral grains and subdued earthy luster. Typical granite hardness is about 6–7 Mohs, with no prominent cleavage as a whole and specific gravity around 2.6–2.7.
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Physical properties
Coarse crystalline texture is obscured by weathering; mottled orange-brown surface with darker mineral grains and subdued earthy luster. Typical granite hardness is about 6–7 Mohs, with no prominent cleavage as a whole and specific gravity around 2.6–2.7.
Formation & geological history
An intrusive igneous rock that crystallized slowly from silica-rich magma deep underground, commonly during Precambrian to Phanerozoic mountain-building events; its orange rind likely reflects surface oxidation and chemical weathering.
Uses & applications
Granite is widely used for building stone, countertops, monuments, aggregate, and landscaping; this rounded piece is mainly suitable as a curiosity, garden stone, or teaching specimen.
Geological facts
The rounded shape indicates transport and abrasion by a stream, beach, or glacial environment. The rusty coloration commonly comes from oxidation of iron-bearing minerals or staining by iron oxides.
Field identification & locations
Look for interlocking visible quartz and feldspar grains, occasional black mica, and a hard surface that can scratch glass; a streak, density, or fresh broken face would improve identification. Common worldwide, especially in glaciated and mountainous regions.
