igneous

Vesicular Basalt (Lava Rock)

Aphanitic Mafic Igneous Rock

Hardness: 5-6 (Mohs scale); Color: Dark grey, black, or reddish-brown; Luster: Dull/Earthy; Crystal Structure: Very fine-grained (aphanitic) with vesicular (porous) texture; Specific Gravity: 2.8-3.0

Hardness: 5-6 (Mohs scale)
Color: Dark grey, black, or reddish-brown
Luster: Dull/Earthy

Identified May 9, 2026More igneous →

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Physical properties

Hardness: 5-6 (Mohs scale); Color: Dark grey, black, or reddish-brown; Luster: Dull/Earthy; Crystal Structure: Very fine-grained (aphanitic) with vesicular (porous) texture; Specific Gravity: 2.8-3.0

Formation & geological history

Formed during volcanic eruptions when lava containing a high concentration of dissolved gases cools rapidly on the Earth's surface. The gas bubbles are trapped as the rock solidifies, creating the characteristic holes or vesicles.

Uses & applications

Used in construction for road base and concrete aggregate, in landscaping as decorative stone, for outdoor gas grills, and as abrasive pumice alternatives.

Geological facts

Basalts are the most common volcanic rock on Earth and also cover much of the surface of the Moon, Mars, and Venus. The vesicles can sometimes later fill with minerals like quartz or calcite to form amygdaloidal basalt.

Field identification & locations

Identified in the field by its dark color, high density (when not too porous), and presence of small, rounded pits or holes. Commonly found in volcanic regions such as Hawaii, Iceland, and the Pacific Northwest.

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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

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral