igneous
Gabbro (likely with Pyrite/Sulfide mineralization)
Mafic Intrusive Igneous Rock
Hardness: 6-7 (Mohs scale), Color: Dark gray to black with metallic flecks, Luster: Phaneritic (medium to coarse-grained) with metallic inclusions, Crystal structure: Holocrystalline, Specific gravity: 2.7-3.3
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Mohs scale), Color: Dark gray to black with metallic flecks, Luster: Phaneritic (medium to coarse-grained) with metallic inclusions, Crystal structure: Holocrystalline, Specific gravity: 2.7-3.3
Formation & geological history
Formed by the slow cooling of magnesium-rich and iron-rich magma deep beneath the Earth's surface (plutonic). This specimen appears to have undergone secondary mineralization, possibly creating the sulfide (pyrite) inclusions seen as gold-colored flecks.
Uses & applications
Used in the construction industry as 'black granite' for countertops, floor tiles, and as road metal (crushed stone). It is also a source of trace metals like nickel, chromium, and platinum.
Geological facts
Gabbro is the intrusive equivalent of basalt and makes up a significant portion of the Earth's oceanic crust. Some gabbros contain layers of magnetite or ilmenite that are mined for iron and titanium.
Field identification & locations
Identified by its dark color, coarse grain size (visible crystals), and lack of quartz. In the field, it is often found in large plutons or sills. Collectors value specimens with distinct mineral inclusions.
