Molybdenite with Quartz
specimen number:
2262276
location:
Questa, Taos Co., New Mexico, USA
description: The Questa mine, located in the Taos Range of the Sangre de Cristo Mountains near the town of Questa in Taos County, New Mexico, was a major underground and open-pit molybdenum extraction facility. Geologically, the deposit is a world-class Climax-type porphyry molybdenum system associated with the early Miocene-age Questa caldera complex, where multiple phases of highly evolved granitic and aplitic porphyry stocks intruded into overlying volcanic and Precambrian basement rocks. Hydrothermal fluid fracturing generated an intricate stockwork of quartz-molybdenite veins and localized magmatic-hydrothermal breccia pipes, precipitating massive quantities of molybdenite along with minor pyrite, fluorite, and chalcopyrite within the highly altered igneous matrices. Historically, the outcrop was initially mistaken for graphite around 1916, but its true identity was recognized by 1918, leading to the formation of the Molybdenum Corporation of America (Molycorp) which initiated underground operations in 1920. High-grade underground vein extraction continued until 1958, after which Molycorp transitioned the site into a massive, low-grade open-pit mining operation that ran from 1965 until 1983. Corporate operations returned to underground mechanized block-caving in 1983, with production continuing intermittently under Chevron Mining Inc. through various economic and regulatory cycles until persistently low global molybdenum prices and high structural operating costs forced the permanent cessation of all mining and milling operations in 2014.
Rich metallic crystalline and masses of molybdenite throughout matrix with minor quartz. Good locality example for the species. The specimen comes with a previous collection data card that provides an acquisition date in 1960.
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