igneous

Basalt with Quartz/Calcite Vein

Amygdaloidal Basalt (matrix) with Mineral Vein filling

Hardness: 6-7 (basalt matrix), 3 (if calcite vein) or 7 (if quartz vein). Color: Dark grey to charcoal matrix with a white crystallised vein. Luster: Dull/earthy matrix with a vitreous vein. Crystal Structure: Aphanitic (fine-grained) matrix.

Color: Dark grey to charcoal matrix with a white crystallised vein
Luster: Dull/earthy matrix with a vitreous vein

Identified March 20, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava. The white vein formed later via hydrothermal activity, where mineral-rich hot water flowed through a crack in the cooling rock and deposited crystals. Common in volcanic terrains across all geological ages.

Uses & applications

Basalt is used extensively as crushed stone for road base, concrete aggregate, and railroad ballast. Small river-worn specimens like this are primarily used for landscaping, decorative gravel, or as pocket stones for collectors.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The white line is often called a 'Wishing Line' in folklore; it is said that if you find a rock with a continuous line circling it, it will grant a wish.

Field identification & locations

Identify in the field by its high density, dark color, and fine texture. The white vein will not scratch easily if quartz, but will bubble with weak acid (vinegar) if it is calcite. Commonly found on beaches, riverbeds, and volcanic fields.

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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)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral