igneous

Scoria

Scoria (vesicular volcanic rock)

Hardness: 5-6 Mohs; Color: Dark brown, black, or reddish-brown; Luster: Dull (sub-vitreous); Crystal Structure: Aphanitic with high vesicularity; Specific Gravity: Low (often floats briefly/sinks slowly)

Hardness: 5-6 Mohs
Color: Dark brown, black, or reddish-brown
Luster: Dull (sub-vitreous)

Identified May 28, 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 during explosive volcanic eruptions where magma containing high concentrations of gas is ejected into the air, cooling quickly and trapping gas bubbles as vesicles.

Uses & applications

Used extensively in landscaping, gas grill lava rocks, high-temperature insulation, and as a lightweight aggregate in concrete or drainage systems.

Geological facts

Scoria differs from pumice because it has larger vesicles and thicker cell walls, making it denser. If it has enough trapped air, it can sometimes be mistake for pumice.

Field identification & locations

Identify by its rough, vesicular (holed) surface and dark color. Common in volcanic regions like Iceland, Hawaii, and Italy. Often found near cinder cones.

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