igneous

Basalt with Vesicles

Vesicular Basalt (comprising Plagioclase Feldspar, Pyroxene, and Olivine)

Hardness: 6.0 (Mohs scale); Color: Dark grey to black or brownish-red; Luster: Dull to earthy; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0; Contains vesicles (gas bubbles).

Hardness: 6
Color: Dark grey to black or brownish-red
Luster: Dull to earthy

Identified March 29, 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 rapid cooling of magnesium-rich and iron-rich lava at the surface of a terrestrial planet or moon. The gas bubbles (vesicles) are trapped as the lava solidifies. Common in volcanic fields globally.

Uses & applications

Used in construction as crushed stone, for road base, concrete aggregate, and railroad ballast. Highly vesicular varieties (scoria) are used in landscaping and as thermal insulation.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also the primary rock type on the Moon's maria and surface of Mars.

Field identification & locations

Identify in the field by its dark color, heavy weight (density), and the presence of small circular pits (holes) where gas was trapped. Frequently found in volcanic regions like Hawaii, Iceland, or the Pacific NW.

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