igneous

Basalt with Calcite Veins

Basalt (containing CaCO3 inclusions)

Hardness: 5-6 (Basalt) / 3 (Calcite); Color: Dark grey to black matrix with white or light grey veins; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained) matrix; Specific gravity: 2.8-3.0.

Hardness: 5-6 (Basalt) / 3 (Calcite)
Color: Dark grey to black matrix with white or light grey veins
Luster: Dull to sub-metallic

Identified February 15, 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 veins are secondary mineralizations (often calcite or quartz) that filled cracks in the rock via hydrothermal activity long after the initial volcanic event.

Uses & applications

Common basalt is used extensively in construction (aggregate, road base), while rounded river stones are used in landscaping and decorative gardening.

Geological facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The white veins shown in the specimen act like a geological record of seismic activity that once fractured the rock.

Field identification & locations

Identify in the field by its heavy weight relative to size, dark color, and the presence of white crystalline lines that do not scratch as easily as the rock itself (if quartz) or fizz with acid (if calcite). Found globally in volcanic regions and riverbeds.

Other igneous specimens

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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

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Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral