Igneous

Diorite

Plutonic Igneous Rock (Intermediate Composition)

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (mottled black and white). Luster: Phaneritic (coarse-grained) with sub-vitreous crystals. Crystal Structure: Monoclinic/Triclinic minerals; specific gravity: 2.8-3.0.

Hardness: 6-7 on Mohs scale
Color: Salt-and-pepper (mottled black and white)
Luster: Phaneritic (coarse-grained) with sub-vitreous crystals

Identified March 23, 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 through the slow cooling of magma beneath the Earth's surface in volcanic arcs and at subduction zones. Typically associated with mountain building through various geological eras.

Uses & applications

Used primarily as crushed stone for road construction and as a decorative stone for countertops, pavers, and building facades. Historically used in ancient Egypt and Mesopotamia for carving hard-stone sculptures.

Geological facts

Diorite was used to carve the Code of Hammurabi, one of the oldest deciphered writings of significant length in the world, due to the rock's extreme durability and hardness.

Field identification & locations

Identify in the field by its phaneritic texture with a roughly equal mix of light plagioclase feldspar and dark minerals like hornblende or biotite. It lacks the pinkish potassium feldspar found in granite and the higher concentration of quartz. Often found in batholiths and mountain ranges like the Andes.

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