Alteration
131substantial alteration — major change, drastic change …
132hydrothermal alteration — GLOSSARY OF VOLCANIC TERMS Changes in rocks or minerals brought about by metasomatism with hydrothermal fluids (generally hot water) …
131substantial alteration — major change, drastic change …
132hydrothermal alteration — GLOSSARY OF VOLCANIC TERMS Changes in rocks or minerals brought about by metasomatism with hydrothermal fluids (generally hot water) …