Davidson, Glacier Gulch, Yorke - Hardy, Hudson Bay Mountain

British Columbia, Canada

Main commodities: Mo W
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The Davidson porphyry molybdenum deposit, also previously known as Glacier Gulch, Yorke-Hardy and Hudson Bay Mountain is located 10 km NW of Smithers in central-west British Columbia, Canada.

The oldest and most widespread lithologic unit in the vicinity of the Davidson deposit, which is developed on Hudson Bay Mountain, is the Lower-Middle Jurassic Hazelton Group andesite and tuffs which are overlain by Lower-Upper Cretaceous Skeena Group sediments.

The volcanic sequence is intruded by a concealed, large, discordant and differentiated granodiorite sheet, the Late Cretaceous to Early Tertiary (73 to 67 Ma) Hudson Bay Mountain stock, which is estimated to be 550 m thick and is developed parallel to the conrtact of, and above a larger quartz monzonite mass.

From top to bottom the Hudson Bay Mountain stock comprises aplitic granodiorite, porphyritic granodiorite and granodiorite, respectively and contains blocks of Hazelton volcanics which may be hundreds of metres in length. Lamprophyre dykes crosscut both the granodiorite and Hazelton rocks.

The Hudson Bay stock is cut by an associated, oval shaped rhyolite porphyry plug and radial quartz-feldspar porphyry dykes. A quartz stockwork cap and a high silica zone are developed at the upper contact of the rhyolite plug.

Molybdenite mineralisation has been encountered over a surface area of approximately 2500x1500 m and a vertical interval of 2100 m, and is surrounded by an envelope of base metal veins over a radius of up to 8 km. High-grade molybdenum zones is concentrated in the lower portion of the differentiated granodiorite sheet which acts as an important lithologic control on mineralisation.

Molybdenite occurs in three styles, as follows:

i). Early fine-grained, relatively low grade, hairline stockwork veins characterised by potassic alteration;
ii). Domal shaped zones of fine-grained, and high-grade, banded quartz-molybdenite veins associated with phyllic;
iii). Spectacular, high grade molybdenite crystals up to 5 cm long occur in coarse-grained quartz-molybdenite veins characterized by potassic alteration envelopes.

A tungsten rich zone generally straddles the upper 0.2 per cent molybdenum boundary and occurs as:

i). Scheelite in Quartz-magnetite-potassium feldspar veins which formed prior to the coarse-grained quartz-molybdenite veins.
ii). Rare disseminations of scheelite associated with andradite garnet, epidote and quartz assemblages formed prior to the fine-grained hairline stockwork veins.
iii). Minor amounts of wolframite which are found downdip from the granodiorite sheet.

Late-stage veining contains pyrite, chalcopyrite, sphalerite and carbonate. The source of the mineralising fluids is thought to be the Hudson Bay Mountain stock due to its spatial relationship.

The original Yorke-Hardy resource was estimated at 90 Mt @ 0.297% MoS2 (0.178% Mo) and 0.04% WO3 (0.032% W) (Climax, Canada)

An estimated resource in 1981 was: 125.5 Mt @ 0.157% Mo, 0.0238% W (Steininger in 1981).

Alternative resource estimates were: 120 Mt @ 0.254% MoS
2 (0.152% Mo), including 24.2 Mt @ 0.4% MoS2 (0.24% Mo)
    (Giroux Consultants Ltd, 1998)

Measured + indicated resources in 2005 were: 83 Mt @ 0.295% MoS
2 (0.176% Mo) (Blue Pearl website)

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
   Selected References:
Bright M J and Jonson D C,  1976 - Glacier Gulch (Yorke-Hardy): in Sutherland Brown A (Ed.) 1976 Porphyry Deposits of the Canadian Cordillera Canadian Institute of Mining and Metallurgy,   Special Volume 15, pp 455-461

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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