Gabbrolike

Gabbrolike is an adjective used in geology and petrology to describe rocks that resemble gabbro in texture or mineral composition. In practice, a rock described as gabbrolike typically has a coarse-grained, holocrystalline (phaneritic) texture and a mafic mineral assemblage similar to gabbro, though it may not meet the formal mineralogical criteria to be classified as true gabbro.

Field notes or petrographic descriptions may use gabbrolike to indicate rocks dominated by plagioclase feldspar with pyroxene (and sometimes minor olivine or amphibole) but with variation in grain size, modal proportions, or alteration that prevents a definitive gabbro label. The term is descriptive rather than taxonomic.

It is often applied to rocks that crystallized at depth (plutonic or lower crustal environments) or to coarse-grained lithologies that resemble gabbro but occur in mixed or layered intrusions, cumulates, or contact-metamorphosed counterparts. In formal classifications, such rocks would be further analyzed to determine exact modal makeup and place within igneous rock nomenclature (for example as gabbro, diorite, or gabbronorite).

Because gabbrolike is not a formal term, its usage varies by author and region. It remains a practical descriptor in fieldwork and preliminary reports, helping to convey similarity to gabbro while awaiting detailed analysis.