igneous

Basalt with Scoria/Vesicular Texture

Vesicular Basalt (Iron-rich/Oxidized)

Hardness: 5-6 (Mohs scale); Color: Reddish-brown, purple-grey, or dark maroon; Luster: Dull/Earthy; Structure: Aphanitic (fine-grained) with vesicles (gas bubbles); Cleavage: None (conchoidal fracture); Specific Gravity: 2.8–3.0

Hardness: 5-6 (Mohs scale)
Color: Reddish-brown, purple-grey, or dark maroon
Luster: Dull/Earthy

Identified March 14, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The pits (vesicles) are created by trapped gas bubbles that escaped as the pressure dropped during eruption. The reddish/purple tint indicates oxidation of iron-rich minerals during cooling.

Uses & applications

Commonly used as aggregate in heavy construction, road base, decor in landscaping, and occasionally as a natural abrasive or 'lava stone' in BBQ grills and jewelry.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. When basalt contains a high volume of these gas bubbles, it is referred to as scoria.

Field identification & locations

Identify in the field by its weight (denser than it looks), numerous small holes or pits on the surface, and fine-grained texture. Frequently found in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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)

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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

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

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Magnetite

Magnetite (Fe3O4)

mineral