igneous
Quartz-rich granite or granitic pegmatite cobble
Granite/pegmatite, chiefly quartz (SiO₂) with feldspar and minor iron-oxide staining
AI-generated identification · may be incorrectCoarse crystalline texture; milky-white to pink quartz/feldspar with reddish-brown weathering. Quartz hardness 7, vitreous to dull luster, no cleavage; feldspar is typically Mohs 6 with two cleavages. Exact identification is limited by the rounded, weathered surface.
Identified More igneous →
Explore Quartz-rich granite or granitic pegmatite cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse crystalline texture; milky-white to pink quartz/feldspar with reddish-brown weathering. Quartz hardness 7, vitreous to dull luster, no cleavage; feldspar is typically Mohs 6 with two cleavages. Exact identification is limited by the rounded, weathered surface.
Formation & geological history
An intrusive igneous rock that crystallized slowly from silica-rich magma, commonly in continental crust; its age may range from Precambrian to much younger depending on locality. Weathering and stream or glacial transport rounded the specimen.
Uses & applications
Granite is used for building stone, countertops, monuments, aggregate, and landscaping; attractive pieces are collected or polished, but this example appears common and not gem-grade.
Geological facts
The white translucent areas are likely quartz, while pink and rusty zones are feldspar altered or stained by iron oxides. Dark flecks may be mica or small mafic minerals.
Field identification & locations
Look for interlocking visible crystals and a hard, nonporous surface; quartz will scratch glass, whereas feldspar generally will not. Common worldwide in granite terrains and gravel deposits.
