Does Basalt Contain Quartz?

A basalt is a fine-grained basic igneous rock containing essential calcic plagioclase feldspar and pyroxene (usually Augite), with or without olivine. Basalts can also contain quartz, hornblende, biotite, hypersthene (an orthopyroxene) and feldspathoids.

Is there quartz in basalt?

Basalts are common aphanitic igneous extrusive (volcanic) rocks. Basalts are composed of minute grains of plagioclase feldspar (generally labradorite), pyroxene, olivine, biotite, hornblende and <20% quartz.

Why is quartz in basalt?

Isolated bodies of volcanic rocks heretofore but little known and found in the southern Sierra Nevada are described Olivine basalts containing well defiled quartz xenocrysts are common. The hypothesis is advanced that the quartz is derived from the alteration of numerous inclusions of grandiorite in the volcanic rocks.