granodiorite

(petrology) A visibly crystalline plutonic rock composed chiefly of sodic plagioclase, alkali feldspar, quartz, and subordinate dark-colored minerals.

A phaneritic (visibly crystalline) plutonic rock composed chiefly of sodic plagioclase (oligoclase or andesine), alkali feldspar (microcline or orthoclase, usually perthitic), quartz, and subordinate dark-colored (mafic) minerals (biotite, amphibole, or pyroxene). Granodiorite is intermediate between granite and quartz diorite (tonalite). For convenience granite and granodiorite are commonly grouped and referred to as granite. See also Granite; Igneous rocks.

For more information on granodiorite, visit Britannica.com.

A sample of granodiorite rock

Granodiorite (IPA: /ˌgɹanə(ʊ)ˈdaɪəɹaɪt, ˌgɹeɪn-/) is an intrusive igneous rock similar to granite, but contains more plagioclase than potassium feldspar. It usually contains abundant biotite mica and hornblende, giving it a darker appearance than true granite. Mica may be present in well-formed hexagonal crystals, and hornblende may appear as needle-like crystals.

On average the upper continental crust has the same composition as granodiorite.

The Rosetta Stone was carved out of grandiorite.

External links

• Granodiorite definition at USGS (public domain source)

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