How can you distingish between feldspar and quartz when lookling at an igneous rock?
gabbro is the intrusive equivalent of basalt, and their mineralogy is the comparable. The mineralogy is predominantly Plagioclase feldspar (not orthoclase) and pyroxene. they could incorporate some amphibole and olivine if very common.
I could not find citations where the two minerals were in direct contact with each other, but they can exist in the same rock specimens. See this article: 74.125.47.132/search?q=cache:fu_H...
Yes. As you pointed out, the olivine is the first to form and the quartz is the last to form as the temperature falls over time. You can certainly find bits of olivine in granite that is mostly quartz and feldspar.
why do we find bits of olivine and quartz in the same rock?
