igneous

Basalt (Vesicular)

Basalt (mostly plagioclase, pyroxene, and olivine)

Hardness: 6 (Mohs scale); Color: dark grey to black or brownish-red; Luster: dull to metallic-submetallic; Crystal structure: aphanitic (fine-grained) often with vesicles (bubbles); Density: 2.8–3.0 g/cm³.

Hardness: 6 (Mohs scale)
Color: dark grey to black or brownish-red
Luster: dull to metallic-submetallic

Identified April 5, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. Most common rock type in Earth's crust (oceanic floor).

Uses & applications

Used primarily in construction for crushed stone, aggregate in concrete and asphalt, and high-quality specimens are sometimes used in aquarium decor or landscaping (lava rock).

Geological facts

Vesicular basalt is the result of gas bubbles escaping as the lava cools. It makes up the majority of the ocean floor and is the most common volcanic rock on Earth and Mars.

Field identification & locations

Identify by its dark color, heavy weight (relative to size), and presence of tiny holes (vesicles). It is commonly found near volcanic sites or in areas with ancient lava flows.

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