igneous

Diorite

Diorite (Intermediate intrusive igneous rock)

Hardness: 6 to 7 on the Mohs scale. Color: Mottled black and white (salt and pepper appearance). Luster: Phaneritic (crystalline) and somewhat dull to sub-vitreous. Structure: Coarse-grained intrusive. Specific Gravity: 2.8 to 3.0.

Hardness: 6 to 7 on the Mohs scale
Color: Mottled black and white (salt and pepper appearance)
Luster: Phaneritic (crystalline) and somewhat dull to sub-vitreous

Identified May 25, 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 below the Earth's surface in volcanic arcs and mountain building zones. It is commonly associated with subduction zones and can range in age from Precambrian to Cenozoic.

Uses & applications

Used in construction as crushed stone for road base and drainage. In polished form, it is used for building facades, floor tiles, and cemetery markers (similar to granite).

Geological facts

Diorite was used in ancient Egypt and Mesopotamia for sculptures due to its hardness and durability. The famous Code of Hammurabi was inscribed on a diorite stele.

Field identification & locations

Identify by its 'salt and pepper' look, where dark minerals (biotite/amphibole) and light minerals (plagioclase feldspar) are present in roughly equal amounts. It lacks the pinkish potassium feldspar or high quartz content of granite.

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

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral