igneous and metamorphic

Glacially transported granite and gneiss boulders

Granite (quartz–feldspar–mica); banded specimens likely gneiss

AI-generated identification · may be incorrect

Typically coarse-grained, gray to pink, with visible quartz, feldspar, and dark mica; vitreous quartz and feldspar luster, Mohs hardness about 6–7, massive granite texture or foliated gneiss banding, with poor cleavage overall.

Identified August 11, 2026More igneous and metamorphic →

Explore Glacially transported granite and gneiss boulders in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Granite crystallized slowly from magma deep in the crust, while gneiss formed by high-grade metamorphism; these rocks commonly formed during Precambrian to Paleozoic mountain-building and were later exposed and transported by Pleistocene glaciers.

Uses & applications

Used as crushed aggregate, riprap, building stone, paving, monuments, and landscaping boulders; attractive polished granite is also used for countertops and memorials.

Geological facts

The rounded, weathered shapes and mixed lithologies are characteristic of glacial erratics and shoreline riprap rather than a single natural outcrop.

Field identification & locations

Identify granite by interlocking light and dark crystals; gneiss commonly shows alternating mineral bands. Common around formerly glaciated regions, including the northern United States, Canada, and Scandinavia.