igneous

Vesicular Basalt with Secondary Mineral Inclusions

Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Hardness: 5-6 Mohs. Color: dark gray to black matrix with light gray/white amygdales. Luster: dull to earthy. Structure: vesicular/amygdaloidal. Specific gravity: 2.8-3.0.

Hardness: 5-6 Mohs
Color: dark gray to black matrix with light gray/white amygdales
Luster: dull to earthy

Identified February 22, 2026More igneous →

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Physical properties

Hardness: 5-6 Mohs. Color: dark gray to black matrix with light gray/white amygdales. Luster: dull to earthy. Structure: vesicular/amygdaloidal. Specific gravity: 2.8-3.0.

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The holes (vesicles) were formed by escaping gas bubbles, some of which have been filled with secondary minerals like zeolite or calcite over geological time.

Uses & applications

Basalt is used extensively in construction as aggregate for roads, railroad ballast, and in the production of high-strength stone fibers. Rare amygdaloidal specimens are kept by hobbyist collectors for their unique textures.

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 in abundance on the Moon and Mars.

Field identification & locations

Identified by its heavy weight, dark color, and characteristic 'pockmarked' or bubbly surface. Common in volcanic regions like Hawaii, the Pacific Northwest, and Iceland.

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