Gabbro vs. Diorite — What's the Difference?

Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt.

Diorite ( DY-ə-ryte) is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-silica (mafic) gabbro and high-silica (felsic) granite.

A usually coarse-grained igneous rock composed chiefly of pyroxene and calcic plagioclase feldspar. Also called norite.

Any of various dark, granite-textured, crystalline rocks rich in plagioclase feldspar and having little quartz.

(rock) Originally, a kind of serpentine; now generally a coarsely crystalline, igneous rock consisting of lamellar pyroxene and labradorite.

(rock) A grey intrusive igneous rock composed mostly of plagioclase feldspar, biotite, hornblende and/or pyroxene.

A name originally given by the Italians to a kind of serpentine, later to the rock called euphotide, and now generally used for a coarsely crystalline, igneous rock consisting of lamellar pyroxene (diallage) and labradorite, with sometimes chrysolite (olivine gabbro).

An igneous, crystalline in structure, consisting essentially of a triclinic feldspar and hornblende. It includes part of what was called greenstone.

One of a family of granular intrusive rocks

A granular crystalline intrusive rock