igneous
Vesicular Basalt with Siltstone
Mafic Volcanic Rock (Basaltic Composition)
Hardness: 6 (Basalt) to 3-4 (Secondary infill), Color: Reddish-brown surface weathering with dark grey-green interior, Luster: Dull or earthy, Structure: Vesicular with small pits/holes, Specific Gravity: 2.8-3.1
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Physical properties
Hardness: 6 (Basalt) to 3-4 (Secondary infill), Color: Reddish-brown surface weathering with dark grey-green interior, Luster: Dull or earthy, Structure: Vesicular with small pits/holes, Specific Gravity: 2.8-3.1
Formation & geological history
Formed from cooled lava flows rich in gas bubbles (vesicles). The reddish hue suggests oxidation (rusting) of iron-rich minerals like olivine or pyroxene over millions of years. This specimen appears water-worn or tumbled.
Uses & applications
Construction aggregate, road base, landscaping stone, and occasionally used in aquarium décor or as a basic mineral specimen for students.
Geological facts
Basalt is the most common volcanic rock on Earth and also makes up most of the ocean floor and the lunar maria on the Moon.
Field identification & locations
Identify by its weight (dense), dark interior color when chipped, and the presence of small holes (vesicles). It is commonly found in volcanic regional belts or riverbeds downstream from volcanic sources.
