Lindgrenite

lindgrenite

antlerite

powellite

brochantite

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Formula: Cu3(Mo6+O4)2(OH)2
Anhydrous molybdate
Specific gravity: 4.2
Hardness: 4½
Streak: Pale green
Colour: Green, yellowish green, pale green to yellow-green in transmitted light
Solubility: Readily soluble in HCl and HNO3.
Environments

Hydrothermal environments

Lindgrenite is an uncommon secondary mineral in the oxidised zone of molybdenum-bearing copper deposits. Associated minerals include antlerite, molybdenite, powellite, brochantite, chrysocolla, limonite, iron oxides and quartz (HOM, Mindat).

Localities

At Tierra Amarilla, Copiapó Province, Atacama, Chile, lindgrenite occurs with szenicsite (Dana).

At the type locality, the Chuquicamata mine, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile, lindgrenite occurs in veinlets in limonitic quartz (AM 20.484-491), associated with quartz, antlerite, limonite and hematite (Dana, Mindat).

At the Childs-Adwinkle mine, Copper Creek, Bunker Hill District, Pinal county, Arizona, USA, lindgrenite occurs as patches of minute crystals, usually occurring in divergent clusters with brochantite (R&M 96.2.155).

At the Tussel Occurrence, Seven Devils District, Adams county, Idaho, USA, lindgrenite occurs on tactite collected from the mine dump. The specimen came from a contact between diorite and marble. The matrix of the lindgrenite is hard granular tactite composed largely of quartz with subordinate amounts of hastingsite, epidote and garnet.
Prior to oxidation the rock contained abundant bornite, molybdenite, a few grains of molybdenum-bearing scheelite, and probably carbonate minerals. Oxidation has converted the bornite almost completely to limonite, and its copper content has been dispersed in chrysocolla, brochantite, lindgrenite, and other secondary copper minerals. Some of the molybdenite is still present as bright silvery plates. Elsewhere molybdenite has been altered to pseudomorphs of powellite. A second variety of pale green powellite partly fills a cavity lined with quartz crystals and is thought to be of supergene origin. The molybdenum-bearing scheelite is the least affected of the ore minerals, but on most of the grains an outer shell has been altered to cuprotungstite.
The lindgrenite occurs as veinlets, crusts, and possibly minor replacements of pseudomorphous powellite. Some cavities formerly occupied by molybdenite are now lined with drusy crusts of lindgrenite (AM 38.903-911).

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