igneous

Basalt with vesicles/amygdules

Basalt (containing volcanic glass and plagioclase)

Hardness: 6-7 (Mohs); Color: Dark grey to black with light tan/white inclusions; Luster: Dull to vitreous; Structure: Aphanitic with vesicular or amygdaloidal texture; SG: 2.8-3.0

Hardness: 6-7 (Mohs)
Color: Dark grey to black with light tan/white inclusions
Luster: Dull to vitreous

Identified April 11, 2026More igneous →

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Physical properties

Hardness: 6-7 (Mohs); Color: Dark grey to black with light tan/white inclusions; Luster: Dull to vitreous; Structure: Aphanitic with vesicular or amygdaloidal texture; SG: 2.8-3.0

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. The lighter spots (amygdules) are formed when gas bubbles (vesicles) are filled by secondary minerals like quartz or calcite over time.

Uses & applications

Used in construction (crushed stone), road base, concrete aggregate, and decorative landscaping.

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 extensively on the Moon and Mars.

Field identification & locations

Identify by its dark color, heavy weight (high density), and fine-grained texture. Often found in volcanic regions or as rounded river/beach stones. Collectors look for unique amygdaloidal patterns.

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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