igneous

Scoria (Lava Rock)

Vesicular Basalt / Scoria

Hardness: 5-6 (Mohs scale); Color: Black to dark grey; Luster: Dull/Earthy; Structure: Highly vesicular (pitted with air bubbles); Specific Gravity: 0.8 to 2.1 (often floats temporarily)

Hardness: 5-6 (Mohs scale)
Color: Black to dark grey
Luster: Dull/Earthy

Identified March 29, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 5-6 (Mohs scale); Color: Black to dark grey; Luster: Dull/Earthy; Structure: Highly vesicular (pitted with air bubbles); Specific Gravity: 0.8 to 2.1 (often floats temporarily)

Formation & geological history

Formed from gas-rich mafic magma cooling rapidly during a volcanic eruption. The 'holes' are created by trapped gas bubbles (vesicles) as the lava solidifies. It is usually from the Cenozoic era or younger in active volcanic regions.

Uses & applications

Commonly used for landscaping (lava rocks), gas grill heating stones, high-temperature insulation, and lightweight concrete aggregate.

Geological facts

Unlike pumice, which is also vesicular, scoria is denser and will usually sink in water eventually. It is a major component of volcanic cinder cones.

Field identification & locations

Identify in the field by its very light weight relative to appearance, rough/sharp texture, and dark color. Common in volcanic fields like those in Hawaii, Iceland, and the Western United States.

Other igneous specimens

See all

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