| Summary: | Trabajo presentado en el XIX Congreso Peruano de Geología, celebrado en Lima (Perú), del 23 al 26 de septiembre de 2018 Magnetite chemistry is often used to investigate the origin of Iron Oxide-Copper-Gold (IOCG) and Magnetite-Apatite (MtAp) deposits. The present study is a comparison of magnetite compositions from ore, as well as altered and unaltered host rocks from the El Laco and Los Colorados MtAp deposits in northern Chile. Magnetite from a typical andesitic country rock from the Punta del Cobre region in Chile, from the classic Kiruna MtAp deposit in Sweden, from altered and unaltered Icelandic rhyolites, and unaltered granites from the Mojave Desert in the United States are also considered, for context, to assess the compositional variations that occur in magnetite. Trace element chemistry of magnetite in both host rock and ore from El Laco and Los Colorados are consistently distinct from one another (e.g., on plots using Sn, Ga, V, Ti, and Al). Samples from El Laco are most similar to magnetite from Icelandic rhyolites, while Los Colorados compositions are more similar to Mojave granites. Empirical discrimination schemes intended to distinguish magnetite of magmatic vs. hydrothermal origins may need to be re-evaluated, to account for other factors (e.g., coeval phases, tectonic setting and petrogenetic processes, host crust, etc.) involved with elemental availability and partitioning during magnetite crystallization (economic grade or otherwise). Peer reviewed
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