pigeonitephyric

Pigeonitephyric describes a volcanic rock texture characterized by the presence of pigeonite phenocrysts within a fine-grained groundmass. Pigeonite is a clinopyroxene mineral, specifically a calcium-magnesium iron silicate. The term "phyric" refers to the presence of phenocrysts, which are larger, well-formed crystals that are conspicuously visible within the finer-grained matrix or groundmass of the volcanic rock. In a pigeonitephyric texture, these larger pigeonite crystals are the dominant or a significant phenocryst phase.

The groundmass of a pigeonitephyric rock can vary in composition and texture, often being aphanitic (too fine-grained to be seen with the naked eye) or even glassy. The formation of such a texture implies a two-stage cooling history for the magma. Initially, the magma cooled slowly enough to allow the growth of larger pigeonite crystals. Subsequently, the remaining magma erupted to the surface and cooled rapidly, solidifying into the fine-grained or glassy groundmass. The size and abundance of the pigeonite phenocrysts can provide clues about the conditions under which the magma evolved prior to eruption. Pigeonitephyric textures are found in various volcanic rocks, particularly those of intermediate to mafic composition, such as andesites and basalts.