Do Volcanoes Have Minerals?

Do Volcanoes Have Minerals? Do volcanoes have minerals? Precious stones and minerals that are found in volcanoes include opals, obsidian, fire agate, flourite, gypsum, onyx, hematite, and others. Are there minerals in volcanoes? Other than the remnant primary minerals, the volcanic ash contains quartz, tridymite, cristobalite, kaolin-group mineral, alunite, anhydrite, gypsum, pyrophyllite, muscovite, chlorite, K-feldspar,