Gabbros: basic intrusive rocks primarily composed of calcium-rich Plagioclase and mafic minerals such as Pyroxenes, Amphiboles, and Olivines. Their texture is generally holocrystalline hypidiomorphic (in petrography, a granular structure consisting of both idiomorphic minerals with well-formed crystal outlines and allotriomorphic minerals that fill the remaining space). Gabbros are classified based on their dominant mineral component, e.g., Amphibole Gabbros, Olivine Gabbros, etc. Many Gabbros feature secondary minerals resulting from the alteration of Pyroxenes, Amphiboles, or Plagioclase. The most common extrusive rocks with a similar composition are Basalts and Diabases.
