igneous

Basalt

Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Contains plagioclase feldspar, pyroxene, and olivine.

Hardness: 6
Color: Dark grey to black
Luster: Dull to sub-metallic

Identified May 3, 2026More igneous →

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Physical properties

Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Contains plagioclase feldspar, pyroxene, and olivine.

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. It is the most common volcanic rock on Earth.

Uses & applications

Extensively used in construction, such as aggregate for roads, railroad ballast, and concrete. It is also used as a dimension stone for flooring, monuments, and landscaping.

Geological facts

Basalt is the most common rock in Earth's crust and makes up most of the ocean floor. It is also found on the Moon, Mars, and Venus.

Field identification & locations

Identify in the field by its dark color, heavy weight (density), and lack of visible crystals without a magnifying glass. It is commonly found in volcanic regions, oceanic crust, and riverbeds near volcanic flows.

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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