igneous
Diabase (Dolerite)
Mafic intrusive igneous rock
Hardness of 6-7 on the Mohs scale, dark gray to black color with a sub-to-ophitic texture showing lath-like plagioclase crystals, vitreous to dull luster, high specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6-7 on the Mohs scale, dark gray to black color with a sub-to-ophitic texture showing lath-like plagioclase crystals, vitreous to dull luster, high specific gravity around 2.8-3.0.
Formation & geological history
Formed from the cooling of basaltic magma intruded into shallow crustal dikes or sills, typically during various geological eras from Precambrian to Cenozoic.
Uses & applications
Commonly crushed and used as aggregate in construction, road building, railroad ballast, and occasionally as dimension stone known commercially as 'black granite'.
Geological facts
Diabase features a characteristic diabasic or ophitic texture where interlocking plagioclase laths are enclosed by pyroxene crystals, creating an exceptionally tough and durable rock.
Field identification & locations
Identify by its dark gray or greenish-black color, dense weight, and visible interlocking white or light-colored plagioclase crystals within a fine to medium-grained dark matrix. Found globally in ancient and modern volcanic provinces.
