igneous
Scoria
Scoriaceous Basalt
Hardness: 5.5-6.0; Color: reddish-brown to black; Luster: dull to vitreous; Structure: highly vesicular (pitted with gas bubbles); Specific Gravity: 1.0-2.0 (often sinks in water, unlike pumice)
- Hardness
- 5
- Color
- reddish-brown to black
- Luster
- dull to vitreous
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5.5-6.0; Color: reddish-brown to black; Luster: dull to vitreous; Structure: highly vesicular (pitted with gas bubbles); Specific Gravity: 1.0-2.0 (often sinks in water, unlike pumice)
Formation & geological history
Formed from the cooling of gas-rich basaltic or andesitic magma. As the pressure drops during eruption, dissolved gases expand to form bubbles which are trapped as the lava solidifies. Found near cinder cones and volcanic vents.
Uses & applications
Used in landscaping for ground cover, as a drainage stone, in lightweight concrete blocks, for high-temperature insulation, and as an abrasive in stone-washing jeans.
Geological facts
Scoria is often confused with pumice, but it has thicker cell walls and is denser, meaning most scoria specimens will sink in water while pumice floats. The reddish color is usually due to the oxidation of iron within the rock.
Field identification & locations
Identify in the field by its sponge-like or honeycomb appearance and lightweight feel relative to size. It is extremely common in volcanic regions like the American Southwest, Iceland, and Italy.
More like this
Other igneous specimens
Granite
Granite
Igneous
Granite
Granite
Igneous
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Dalmatian Jasper
Aplite with Arfvedsonite inclusions
igneous
Magnetite
Iron(II,III) oxide (Fe3O4)
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