igneous

Olivine Diabase Porphyry

Porphyritic Olivine-Bearing Diabase (Micro-Gabbro)

Hardness: 6-7 on Mohs scale; Color: Mottled green, black, and grey with possible blue-grey weathering; Luster: Vitrous to dull; Crystal structure: Porphyritic (fine-grained matrix with larger visible crystals); Specific gravity: 2.9–3.3 (heavy/dense).

Hardness: 6-7 on Mohs scale
Luster: Vitrous to dull

Identified February 16, 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-to-rapid cooling of magnesium-rich and iron-rich magma within shallow crustal intrusions such as dikes or sills. These rocks are typically associated with Proterozoic or Mesozoic era volcanic events.

Uses & applications

Used primarily as crushed stone for road construction and high-grade railroad ballast due to its durability. Sometimes used as dimension stone for counter tops or architectural cladding under names like 'Black Granite'.

Geological facts

This specific texture is often referred to as 'leopard stone' or 'snakeskin' in decorative contexts. It provides a window into the geochemical signature of the Earth's mantle at the time of its intrusion.

Field identification & locations

Identify by its 'salt and pepper' or mottled appearance, containing dark pyroxene and olivine crystals set in a lighter plagioclase feldspar matrix. Common in the Palisades Sill (USA), Canadian Shield, and the Karoo Large Igneous Province.

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