igneous
Vesicular Basalt (or Scoria)
Extrusive Igneous Rock (Mafic)
Hardness: 5-6 (Mohs); Color: Grey, brown, or reddish-brown; Luster: Dull/Earthy; Structure: Vesicular (pitted with gas bubbles); Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs)
- Color
- Grey, brown, or reddish-brown
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs); Color: Grey, brown, or reddish-brown; Luster: Dull/Earthy; Structure: Vesicular (pitted with gas bubbles); Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava. The holes (vesicles) are created by trapped gas bubbles that escaped as the lava solidified at the surface.
Uses & applications
Used in landscaping, high-temperature insulation, lightweight concrete aggregate, and as stone for gas grills or saunas.
Geological facts
The holes in this rock are essentially 'frozen bubbles' of volcanic gas. If the rock has more holes than solid mass, it is categorized specifically as scoria.
Field identification & locations
Identified by its lightweight feel compared to solid rock and its distinctive Swiss-cheese texture. Commonly found in volcanic fields or near ancient lava flows.
