igneous

Quartz-veined Basalt

Amygdaloidal or Porphyritic Basalt with Silicon Dioxide (SiO2) vein

Hardness: 6-7 (Mohs scale), Color: Dark grey/green matrix with white/tan vein, Luster: Dull/earthy matrix with vitreous vein, Structure: Fine-grained (Aphanitic), Cleavage: None (conchoidal fracture on vein), Specific Gravity: 2.7–3.0

Identified March 22, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. The white vein formed later via hydrothermal activity, where mineral-rich water filled a cooling crack and crystallized as quartz or calcite.

Uses & applications

Basalt is primarily used in construction as crushed stone for road base, concrete aggregate, and railroad ballast. This specific small specimen is primarily of interest for amateur geology collecting or educational purposes.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The white vein acts as a 'geological clock', showing that the host rock experienced a secondary tectonic or thermal event after it solidified.

Field identification & locations

Identify by its dark, heavy, fine-grained mass and the distinct contrasting mineral line. Often found near tectonic plate boundaries or volcanic island chains. Collectors should look for sharp color contrast and well-defined vein boundaries.

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