igneous

Diorite

Intrusive Igneous Rock (Intermediate Composition)

Hardness: 6-7 Mohs; Color: Salt-and-pepper (mottled black and white); Luster: Dull to sub-vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Presents as varied mineral cleavage; Specific Gravity: 2.8 - 3.0.

Hardness: 6-7 Mohs
Color: Salt-and-pepper (mottled black and white)
Luster: Dull to sub-vitreous

Identified March 28, 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 cooling of magma beneath the Earth's surface in volcanic arcs and mountain building zones. It is an intermediate rock between granite and gabbro, often found in continental crust environments ranging from Precambrian to Cenozoic ages.

Uses & applications

Commonly used as a base material in road construction, building stone, and dimension stone for pavers or countertops. Historically used by ancient civilizations for sculpture due to its extreme durability.

Geological facts

Famous ancient artifacts, such as the Code of Hammurabi on a diorite stele and various Egyptian statues, were carved from this rock because it is harder than granite and holds detail well.

Field identification & locations

Identify in the field by its distinctive 'Dalmatian' appearance: a roughly equal mix of light plagioclase feldspar and dark minerals like hornblende or biotite. It lacks the visible quartz typical of granite. Found worldwide in mountain roots (e.g., Andes, Alps).

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