Basalt
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Mineral NameBasalt
Chemical FormulaComplex, primarily silicates of Ca, Na, Fe, Mg, Al (e.g., plagioclase, pyroxene, olivine)
Mohs Hardness6
Streak ColorGrayish-white to Dark gray
CleavageAbsent (as a rock)
FractureConchoidal to Uneven
Specific Gravity2.9
Colorsdark gray, black
TransparencyOpaque
Type LocalityLa Palma, Canary Islands
Mineral GroupIgneous rock (mafic volcanic)
Usesconstruction aggregate, dimension stone, road base
Associated Mineralsplagioclase, pyroxene, olivine, magnetite, epidote
Raritycommon
Description
This sample is a basalt breccia, featuring angular dark gray to black basalt clasts embedded in a lighter, greenish-gray matrix, which the metadata identifies as epidote. The overall diameter of the sample is 12 cm.
Geological Context
Basalt is an extrusive igneous rock formed from the rapid cooling of mafic lava at or near the Earth's surface, characteristic of oceanic crust and volcanic islands. This specific sample, a breccia, indicates fragmentation and cementation during volcanic activity or subsequent alteration.
