igneous
Vesicular Basalt (or Scoria)
Vesicular Basalt
Hardness: 5-6 (Mohs scale), Color: Dark grey, brownish to black, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained), Cleavage: None, Feature: Highly porous with visible vesicles (gas bubbles)
Identified More igneous →
Explore Vesicular Basalt (or Scoria) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs scale), Color: Dark grey, brownish to black, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained), Cleavage: None, Feature: Highly porous with visible vesicles (gas bubbles)
Formation & geological history
Formed through the rapid cooling of magnesium-rich and iron-rich lava. The holes (vesicles) are created by trapped gas bubbles escaping as the lava solidifies at the surface.
Uses & applications
Used in landscaping, as a construction aggregate, for BBQ grill rocks (lava rocks), and sometimes in drainage systems.
Geological facts
If the rock is so full of vesicles that it becomes lightweight and frothy, it is called Scoria. Unlike pumice, vesicular basalt usually sinks in water because of its higher iron content.
Field identification & locations
Identify in the field by its dark color and distinctive 'holy' or pitted surface. Common in volcanic regions such as Hawaii, Iceland, and the Pacific Northwest.
