Editing Gabbro (section)

=== Subtypes ===
There are a number of subtypes of gabbro recognized by geologists. Gabbros can be broadly divided into leucogabbros, with less than 35% mafic mineral content; mesogabbros, with 35% to 65% mafic mineral content; and melagabbros with more than 65% mafic mineral content. A rock with over 90% mafic mineral content will be classified instead as an [[ultramafic rock]]. A gabbroic rock with less than 10% mafic mineral content will be classified as an anorthosite.<ref name="bgs"/>{{sfn|Philpotts|Ague|2009|p=142}}

A more detailed classification is based on the relative percentages of plagioclase, pyroxene, hornblende, and olivine. The end members are:<ref name="bgs"/>{{sfn|Philpotts|Ague|2009|p=142}}
* Normal gabbro (gabbro ''sensu stricto''<ref name="bgs"/>) is composed almost entirely of plagioclase and [[clinopyroxene]] (typically augite), with less than 5% each of hornblende, olivine, or [[orthopyroxene]]. 
* [[Norite]] is composed almost entirely of plagioclase and [[orthopyroxene]], with less than 5% each of hornblende, clinopyroxene, or olivine.
* [[Troctolite]] is composed almost entirely of plagioclase and olivine, with less than 5% each of pyroxene or hornblende.
* [[Hornblende gabbro]] is composed almost entirely of plagioclase and hornblende, with less than 5% each of pyroxene or olivine.
Gabbros intermediate between these compositions are given names such as [[gabbronorite]] (for a gabbro intermediate between normal gabbro and norite, with almost equal amounts of clinopyroxene and orthopyroxene) or olivine gabbro (for a gabbro containing significant olivine, but almost no clinopyroxene or hornblende). A rock similar to normal gabbro but containing more orthopyroxene is called an orthopyroxene gabbro, while a rock similar to norite but containing more clinopyroxene is called a clinopyroxene norite.<ref name="bgs"/>

[[File:Main ridge of the cuillin in skye arp.jpg|thumb|right|A gabbro landscape – the main ridge of the [[Cuillin]], [[Isle of Skye]], [[Scotland]]]]
[[File:Čizlakit.jpg|230px|thumb|right|Cizlakite sample]]

Gabbros are also sometimes classified as alkali or tholleiitic gabbros, by analogy with [[alkali basalt|alkali]] or [[Tholeiitic magma series|tholeiitic]] basalts, of which they are considered the intrusive equivalents.{{sfn|Allaby|2013|loc="gabbro"}} Alkali gabbro usually contains olivine, nepheline, or [[analcime]], up to 10% of the mineral content,{{sfn|Jackson|1997|loc="alkali gabbro"}} while tholeiitic gabbro contains both clinopyroxene and orthopyroxene, making it a gabbronorite.{{sfn|Allaby|2013|loc="gabbro"}}