Formation of topaz-enriched gneiss in the east-central Colorado Front Range via crystallization of Mesoproterozoic halogen-rich granitic magmas
Metamorphic rocks enriched in economically valuable minerals occur in all mountain belts worldwide, yet their processes of formation are often incompletely understood. Topaz [Al2SiO4(F,OH)2] is a naturally occurring nesosilicate of great economic and industrial value, and is most commonly found in silica-rich igneous rocks. However, conspicuous 70-ft-thick bands of topaz-, sillimanite-, rutile-, and quartz-rich (TSRQ) metamorphic gneiss occur in the Evergreen region of the east-central Front Range, Colorado, immediately adjacent to “normal” amphibolite and pelitic schist horizons. Bulk-rock ...
(For more, see "View full record.")