igneous
Basalt
Basalt
Hardness: 6; Color: dark grey to black; Luster: dull to earthy; Crystal structure: aphanitic (fine-grained); Cleavage: none; Specific gravity: 2.8–3.0
- Hardness
- 6
- Color
- dark grey to black
- Luster
- dull to earthy
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Physical properties
Hardness: 6; Color: dark grey to black; Luster: dull to earthy; Crystal structure: aphanitic (fine-grained); Cleavage: none; Specific gravity: 2.8–3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the surface of a terrestrial planet or a moon.
Uses & applications
Used primarily in construction (crushed stone, concrete aggregate), road base, and high-quality floor tiles or monuments.
Geological facts
Basalt is the most common rock type on Earth's crust and makes up most of the ocean floor; it is also extremely common on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight compared to other rocks, and fine-grained texture; found worldwide in volcanic regions, such as the Giant's Causeway or oceanic ridges.
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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