Diorite is a medium-grained intrusive igneous rock consisting mostly of andesine plagioclase and pyroxene, and small amounts of hornblende and biotite. It is the intrusive equivalent of andesite. A medium-grained diorite contains black hornblende and white plagioclase feldspar.
Gabbro is a dark, medium to coarse-grained intrusive igneous rock composed of calcium plagioclase, pyroxene, and possibly olivine, but no quartz. It is the intrusive equivalent of basalt and the deep intrusive equivalent of diabase.
A coarse-grained gabbro consists of black pyroxene and/or hornblende and white plagioclase feldspar.
Rhyolite is a very fine-grained to glassy extrusive igneous rock (i.e., volcanic), usually light in color but not always, consisting essentially of quartz (silica) and alkalic feldspar. It is the extrusive equivalent of granite. Porphyry is an igneous rock of any composition that contains conspicuous crystals (Phenocrysts) in a fine-grained matrix. A fine-grained rhyolite contains larger pink feldspar Phenocrysts, which gives a porphyritic appearance.
Breccia is a rock consisting of angular fragments in a matrix of finer particles. An intrusion breccia consists of older host rocks (wall rocks) surrounded by younger intrusive igneous rocks.
Diabase Dykes (intrusive relationships)
A dyke is a sheet of intrusive rock that cuts across layering or bedding in the surrounding rocks. Diabase is a dark-colored intrusive rock, found as dykes or sills, composed of mainly feldspar, pyroxene +/- olivine. It is the intrusive equivalent of basalt and the shallow intrusive equivalent of gabbro. The linear, black, diabase dyke shown cuts across (is intrusive into) the layering / banding in older gneisses.