A generalized mineral composition for dacite is intermediate between rhyolite and andesite. It usually contains more quartz than andesite and more plagioclase than rhyolite. The plagioclase feldspars are often oligoclase, andesine or labradorite. Dacite can be considered the fine-grained equivalent of granodiorite.

Plagioclase is the most abundant mineral in many dacites. Other minerals that might be found in dacite include quartz, biotite, hornblende, augite, and enstatite. Dacites consisting mostly of plagioclase and quartz are usually light in color, often white to light gray. Those with abundant hornblende and biotite can be light gray to light brown. The darkest dacites usually contain abundant augite or enstatite.