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Gabbro is known in the construction industry by the trade name of black granite. [31] However, gabbro is hard and difficult to work, which limits its use. [32] The term "indigo gabbro" is used as a common name for a mineralogically complex rock type often found in mottled tones of black and lilac-grey.
Diorite is an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and sometimes pyroxene.The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite.
Examples of phaneritic igneous rocks are gabbro, diorite, and granite. Porphyritic textures develop when conditions during the cooling of magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a ...
Anorthosite (/ ə ˈ n ɔːr θ ə s aɪ t /) is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%).
Generally speaking, phaneritic implies an intrusive origin or plutonic, indicating slow cooling; aphanitic are extrusive or volcanic, indicating rapid cooling. [18] An igneous rock with larger, clearly discernible crystals embedded in a finer-grained matrix is termed porphyry. Porphyritic texture develops when the larger crystals, called ...
The principal difference between norite and gabbro is the type of pyroxene of which it is composed. Norite is predominantly composed of orthopyroxenes, largely high-magnesian enstatite or an iron-bearing hypersthene. The principal pyroxenes in gabbro are clinopyroxenes, generally iron-rich augites. [2] [3]
Hornblende is a common constituent of many igneous and metamorphic rocks such as granite, syenite, diorite, gabbro, basalt, andesite, gneiss, and schist. It crystallizes in preference to pyroxene minerals from cooler magma that is richer in silica and water. [13]
Basalt. A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron.Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite.