igneous

Granite with Mafic Inclusions

Granite (Phaneritic igneous rock composed of Quartz, Feldspar, and Mica)

Hardness: 6-7 (Mohs scale), Color: Light gray matrix with a dark gray/black band, Luster: Dull to pearly, Crystal structure: Phaneritic (visible grains), Cleavage: None for the rock overall, though mineral components may show it.

Identified April 6, 2026More igneous →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed from the slow underwater cooling of magma beneath the Earth's surface (intrusive). The dark band likely represents a mafic inclusion or a small dike of different mineral composition (like diorite or basaltic melt) that intruded the granite body.

Uses & applications

Used primarily in construction (countertops, tiles, paving), monuments, and as crushed stone for road base. Specimens with unique banding are sometimes kept as geological educational samples.

Geological facts

Granite makes up a large portion of the Earth's continental crust. The dark stripes in granite, like the one seen here, are often called 'xenoliths' if they are chunks of older rock that got stuck in the magma, or 'schlieren' if they are concentrated streaks of dark minerals.

Field identification & locations

Identify by its 'salt and pepper' granular appearance and its extreme hardness; it cannot be scratched by a steel knife. Commonly found in mountain ranges and ancient shields like the Canadian Shield.

Other igneous specimens

See all

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral