igneous

Scoria (Lava Rock)

Mafic Vesicular Volcanic Rock

Hardness: 5-6 (Mohs scale); Color: Dark red, black, or dark brown; Luster: Dull to sub-vitreous; Structure: Vesicular (highly porous/holed); Specific Gravity: 0.8-2.1 (relatively light)

Hardness: 5-6 (Mohs scale)
Color: Dark red, black, or dark brown
Luster: Dull to sub-vitreous

Identified March 22, 2026More igneous →

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Physical properties

Hardness: 5-6 (Mohs scale); Color: Dark red, black, or dark brown; Luster: Dull to sub-vitreous; Structure: Vesicular (highly porous/holed); Specific Gravity: 0.8-2.1 (relatively light)

Formation & geological history

Formed from gas-rich mafic magma cooling rapidly during a volcanic eruption. Gases expand and form bubbles (vesicles) while the lava solidifies. It is primarily found in recent volcanic landscapes (Cenozoic era).

Uses & applications

Used widely in landscape gardening, gas grills, high-temperature insulation, drainage systems, and as an abrasive in stone-washing denim.

Geological facts

Scoria is different from Pumice; whereas Pumice is light enough to float on water, Scoria is more dense and usually sinks. It is the primary component of many cinder cones (volcanic peaks).

Field identification & locations

Identify in the field by its sponge-like appearance, sharp edges, and dark color. It is extremely common in volcanic regions like Iceland, Hawaii, and Italy. Collectors value it for terrariums and aquariums.

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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