igneous

Basalt with Quartz Vein

Basalt (Mafic volcanic rock) with secondary Quartz (SiO2) intrusion

Hardness: 6 (basalt) to 7 (quartz); Color: Matte black/dark grey host rock with a translucent white/cream vein; Luster: Dull to sub-vitreous; Structure: Fine-grained/aphanitic matrix with a linear crystalline vein.

Hardness: 6 (basalt) to 7 (quartz)
Luster: Dull to sub-vitreous

Identified May 25, 2026More igneous →

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Physical properties

Formation & geological history

Basalt forms from the rapid cooling of magnesium-rich and iron-rich lava at the surface. The white line is a vein formed later when hydrothermal fluids (hot water) rich in silica filled a fracture in the basalt and crystallized into quartz.

Uses & applications

Basalt is used extensively in construction as crushed stone for roads and concrete. Veined specimens like this are primarily collected for hobbyist interest or used as decorative garden stones.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The presence of a single, clean vein like the one shown is often referred to by collectors as a 'wishing stone' in folklore.

Field identification & locations

Identify in the field by its dark, heavy, fine-grained mass and the distinct color contrast of the vein. Common in volcanic regions, riverbeds, and coastal areas.

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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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Blue Apatite

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

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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Magnetite

Magnetite (Fe3O4)

mineral