Thompson Creek

Idaho, USA

Main commodities: Mo
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The Thompson Creek porphyry molybdenum deposit is located near Challis in east-central Idaho, USA.

The molybdenum mineralisation at Thompson Creek occurs in numerous systematically oriented sets of quartz veins confined to a late magmatic quartz monzonite core within a granodiorite stock. The granodiorite intrudes lower Carboniferous (Mississippian) argillites. Both are overlain by Eocene post mineral Challis Volcanics.

Dating of muscovite and biotite from the quartz-molybdenite vein alteration assemblage returned ages of 85.9±3, and 86.9±3 Ma respectively. The metasomatised quartz-monzonite core occurs within the granodiorite stock, and is interpreted to have developed from the original stock by late magmatic growth of K-feldspar, quartz and biotite.

Molybdenum mineralisation is typically associated with quartz-biotite-pyrite veins, with or without K-feldspar alteration halos, that are contained in the quartz-monzonite core. An age of 88.4 Ma has been obtained from primary biotite in the transition between the quartz-monzonite core and the main granodiorite of the stock.

The mineralisation is related to late phases of the main 94 Ma Idaho Batholith, and not the younger 78 to 68 Ma Boulder Batholith event of the Butte area (Schmidt, et al., 1979).

The orebody has plan dimensions of around 1300 x 300 m and extends over a vertical interval of 550 m, with associated intense potassic alteration (USBM, from unpublished Cyprus reports). The ore appears to straddle the transition zone between the quartz-monzonite core and the granodiorite in its upper sections, being present in both lithologies, near the contact with the intruded meta-sediments, as shown on (Tooker, 1991). The Thompson Creek deposit was initially operated by the Cyprus Minerals Company. In 1992 production amounted to 6750 t of Mo (Am. Mines H'book, 1994, p 66). Currently the mine is owned by Blue Pearl Mining through its holdings in the Thompson Creek Mining Company acquired in late 2006.

Current mineral resources are (Blue Pearl Mining website 2006):

Measured + Indicated - 178.6 Mt @ 0.094% Mo Inferred - 34.5 @ 0.66% Mo

Current reserves are (Blue Pearl Mining website 2006):

Proven + probable - 64.5 Mt @ 0.119% Mo.

The most recent source geological information used to prepare this summary was dated: 2006.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.

  References & Additional Information

Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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