Granophyre

Granophyre (/ˈɡrænəfaɪər/ GRAN-ə-fire;[1][2] from granite and porphyry) is a subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths such as those in the accompanying image.

These textures document simultaneous crystallization of quartz and feldspar from a silicate melt at the eutectic point, perhaps in the presence of a water-rich phase.

[3] Granophyres typically are intrusive rocks that crystallized at shallow depths, and many have compositions similar to those of granites.

Granophyre may also form as the uppermost stratigraphic layer resulting from melting of upper-middle crustal rocks by a meteorite impact.

For example, the upper layer of the Main Mass of the 1850 Ma Sudbury Structure is composed of fine-medium grained granitic rocks with abundant granophyric textures.

Cross-polarized light microscope image of an intergrowth of quartz and alkali feldspar in a granophyre ( Muskox intrusion ), as seen in thin section (Long dimension is 1.5 mm)