Fig. 7. Medium-grained biotite-orthopyroxene gabbro. Plagioclase is An₅₀. Orthopyroxene (tan and blue); quartz (yellow, white). Albite-twinned plagioclase has tiny quartz blebs. Plagioclase in both gabbros locally have circular blebs of quartz that may have crystallized simultaneously during late stages, or this quartz may represent later hydrothermal alteration associated with metasomatism.