igneous

Crushed Stone (Basalt/Gabbro)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Hardness: 6-7 Mohs; Color: Dark grey to black with light speckles; Luster: Dull to sub-metallic; Structure: Fine to medium-grained; Cleavage: Often poor/irregular; Specific Gravity: 2.8-3.0

Hardness: 6-7 Mohs
Color: Dark grey to black with light speckles
Luster: Dull to sub-metallic

Identified April 5, 2026More igneous →

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Physical properties

Hardness: 6-7 Mohs; Color: Dark grey to black with light speckles; Luster: Dull to sub-metallic; Structure: Fine to medium-grained; Cleavage: Often poor/irregular; Specific Gravity: 2.8-3.0

Formation & geological history

Formed through the cooling and solidification of basaltic magma or lava. These rocks are primary components of the oceanic crust and volcanic regions; these specific pieces are typically processed via industrial crushers.

Uses & applications

Extensively used in construction for road base, concrete aggregate, railroad ballast, and landscaping gravel.

Geological facts

Basalt is the most common volcanic rock on Earth and also makes up most of the surface of the Moon and Mars.

Field identification & locations

Identify by its dark color, high density, and fine grain size. Often found in gravel driveways, construction sites, and near volcanic outcroppings.

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