igneous

Vesicular Basalt with Xenocrysts

Mafic Igneous Plutonic/Extrusive Complex

Hardness: 5-6 Mohs; Color: Gray matrix with black glassy inclusions; Luster: Dull matrix, vitreous inclusions; Crystal structure: Aphanitic with visible crystals; Cleavage: None/Irregular

Hardness: 5-6 Mohs
Color: Gray matrix with black glassy inclusions
Luster: Dull matrix, vitreous inclusions

Identified May 10, 2026More igneous →

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Physical properties

Hardness: 5-6 Mohs; Color: Gray matrix with black glassy inclusions; Luster: Dull matrix, vitreous inclusions; Crystal structure: Aphanitic with visible crystals; Cleavage: None/Irregular

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava. The small holes (vesicles) are formed by trapped gas, while the black crystals are minerals that crystallized before the lava erupted.

Uses & applications

Commonly used as aggregate in construction, road base, and for landscaping. Some unique specimens are kept as geological study samples.

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 found on the Moon and Mars.

Field identification & locations

Identify by its dark gray color, heavy weight (high density), and the presence of small holes or embedded dark minerals. Found in volcanic regions globally.

Other igneous specimens

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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