granophyre

Granophyre is a granitoid igneous rock characterized by an intergrowth of quartz and alkali feldspar, a texture known as granophyric texture. This texture arises from the simultaneous crystallization of quartz and feldspar from a magma. In thin section, the granophyric texture appears as irregular patches of quartz embedded within the feldspar crystals, or as radiating or swirling patterns.

The composition of granophyre is typically felsic, similar to granite, with a high proportion of quartz and feldspar, and often containing mica or amphibole. Granophyres are often found in association with mafic intrusions, such as gabbros and dolerites. They can occur as dikes, sills, or as part of larger plutonic bodies. The formation of granophyric texture is thought to occur during the later stages of magma crystallization, when the remaining melt is enriched in silica and alkalis. This texture is also indicative of rapid cooling or specific crystallization conditions. While granophyre shares mineralogical similarities with granite, its distinct texture makes it identifiable. It is a rock type of interest in petrology for understanding magmatic differentiation and crystallization processes.