igneous

Scoria

Vesicular Basalt / Scoria (Mafic volcanic rock)

Hardness: 5-6 (Mohs scale); Color: Dark reddish-brown to black; Luster: Dull/Earthy; Structure: Vesicular (highly porous/holey); Cleavage: None; Specific Gravity: 2.5-3.0 (though it feels light due to air pockets).

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

Identified March 30, 2026More igneous →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed through the rapid cooling of gas-rich mafic magma (lava) ejected from a volcano. The holes, or vesicles, are created by expanding gas bubbles trapped as the lava solidifies. It is usually associated with Cenozoic volcanic activity.

Uses & applications

Commonly used in landscaping (lava rock), gas grill briquettes, high-temperature insulation, drainage stones, and lightweight concrete aggregate. It is rarely used in jewelry due to its abrasive texture.

Geological facts

Scoria is different from pumice because it is mafic (rich in iron and magnesium) and denser; unlike pumice, scoria will usually sink in water. It is a primary component of 'cinder cones' found in volcanic fields.

Field identification & locations

Identify in the field by its distinct 'sponge-like' appearance, rough/sharp edges, and reddish-dark color. It is commonly found in volcanic regions such as the American Southwest, Iceland, and Hawaii.

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

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