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Metaline District - Josephine, Pend Oreille, Grandview, Yellowhead
Washington, USA
Main commodities: Zn Pb

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The Metaline carbonate hosted zinc-lead deposits are hosted by the Cambro-Ordovician Metaline Formation in northeastern Washington state, USA.   Mines include the Josephine, Pend Oreille, Grandview and Yellowhead.

The Metaline Formation lies within the Kootenay arc structural belt that extends from Washington US into British Columbia, Canada and lies between the Purcell anticlinorium to the east and the Valhalla metamorphic complex to the west and contains Proterozoic and Palaeozoic autochthonous shelf deposits (including the Metaline Formation) as well as Palaeozoic to Mesozoic volcanic arc terranes of uncertain palaeogeographic origin.

The Metaline Formation is predominantly a carbonate unit and is approximately 1800 m thick.   It conformably overlies shales of the lower Cambrian Maitlen Formation and is in turn overlain by carbonaceous black siltstones of the Ordovician Ledbetter Formation.

The Metaline Formation is divided into:
• a lower, 300 to 400 m thick, middle Cambrian unit of dark, subtidal lime mudstone and shale, with facies of grey mudstone, ooid-arenite, grey packstone-wackestone, black packstone-wackestone and black mudstone,
• a middle 360 to 1200 m thick unit of sub-tidal dolostones and dolomitic shales with numerous peritidal features, with a series of facies being recognised, and
• the upper 200 to 450 m thick unit of upper Cambrian to lower Ordovician massive grey limestone comprising a sub-tidal, bioturbated lime mudstone and intraclastic packstone.

The Metaline Formation sequence has also been divided into six major lithofacies, four of which host carbonate hosted ("Mississippi Valley" type) mineralisation.   These are:
 i). Light grey (black to grey) bedded, fine to medium grained dolostone, found mainly in the lower part of the Metaline Formation,
 ii). Varied dolostone including black fenestral dolomite, thinly laminated lime mudstone, black massive dolostone and massive lime mudstone, corresponding mainly to the middle member of the Metaline Formation,
 iii). The Josephine Breccia, which is up to 65 m thick and comprises a black fine grained dolostone and matrix supported dolostone breccia with carbonate, quartzite, chert, pyrite and black argillite fragments, found at the top of the Metaline formation.   It may be due to either slumping or solution collapse.
 iv). The Fish Creek Breccia which is found elsewhere in the district and may be equivalent to the Josephine Breccia.
 v) and vi). Two additional facies that are not mineralised, namely thin bedded lime mudstone and grey massive lime mudstone.

These lithofacies are extremely variable and non-continuous.   The mineralisation which post dates the lithofacies is often more continuous than individual facies.

Two types of mineralisation have been recognised, as follows:
 i). Josephine type - which is iron poor and coarse grained, with reddish sphalerite, and is found predominantly in the Josephine lithofacies, a fragmental facies near the upper contact between the Metaline carbonates and the shales of the overlying Ledbetter formation.   Josephine orebodies may be up to1000 m long, 40 m thick and 100 m wide and contain pyrite, galena and sphalerite in the ratio 1:10:70.
 ii). Yellowhead type - which is iron rich, fine grained and often botryoidal, with honey yellow sphalerite, and which forms several planar zones several hundred metres below the Josephine mineralisation, mainly in light grey bedded dolostone facies of the Metaline formation. Pyrite, galena and sphalerite are in the ratio 1:0.1:0.01, with the galena and sphalerite being more abundant in the middle and upper parts of the ore zone, surrounded by a pyrite halo.

Pend Oreille, the most recently operated (to 2019) mine in the district, is of this type, developed within the Yellowhead horizon of the Metaline Formation. The stratabound Yellowhead mineralisation at the Pend Oreille mine is found several hundred metres below the Josephine ore zone, and occurs as at least four stacked and en echelon, tabular to lensoidal, massive, pyrite-sphalerite rich orebodies, the Southwest, Central, Northwest and Warren zones. These are found at the top of and within the bedded dolostone lithofacies of the Metaline Formation (Zieg et al., 2000), with individual pods, lenses and patches of mineralisation crosscutting the lithological facies of the bedded dolostone (St. Marie and Kesler, 2000). Mineralisation is hosted within both brecciated and unbrecciated bedded dolostone and has a medium- to coarsely-crystalline zebra-banded texture, coarse sparry dolomite alteration, and local stratabound breccia which is interpreted to be a solution breccia (Zieg et al., 2000). The orebodies are composed of massive aggregates of Zn- and Pb-rich mineralisation surrounded by pyrite-rich halos crosscutting bedding within the light grey bedded dolostone (St. Marie and Kesler, 2000). They have been described as "jumbled masses of chaotically intergrown colloform/cockade sulphides, carbonates and silicates" (Morton, 1992). The mineralisation occurs as finely colloform and botryoid aggregates of pyrite and red to honey yellow sphalerite with minor galena forming fine layers in a gangue of dolomite, calcite, phengite, jasperoid, quartz and clay minerals (Morton, 1974, 1992; Bending, 1983; Colligan, 1984). The colloform and botryoid aggregates are locally brecciated and cemented by coarse-grained sparry dolomite. Other sulphide textures are typical of regional tectonic deformation and metamorphism, and include: i). fractured pyrite crystals and aggregates with galena filling of the dilatant fractures; ii). fractured sphalerite aggregates and colloform bands and layers; and iii). granoblastic polygonal textures with 120° triple junction points that are locally well developed in pyrite aggregates. Dolomitisation is extensively developed. Pyrite is generally more abundant than sphalerite, and it is commonly restricted to the central and upper parts of the sulphide lenses (St. Marie and Kesler, 2000).

Production and Reserve/Resource statistics for the Metaline deposits include:
  Measured+Indicated+Inferred Reserve 1959 -132 Mt @ 3% Zn, 0.5% Pb (USBM)
  Production, 1915-1950 - 6 Mt @ 3.6% Zn, 1.35% Pb (USBM)
  Production 1915 to closure in 1977:
    Josephine type ore - 12.7 Mt @ 3% Zn, 1.3% Pb (St Marie and Kestler, 2000)
    Yellowhead type ore - 0.73 Mt @ 4.5% Zn, 0.5% Pb (St Marie and Kestler, 2000)
  Reserves in 2000 - 5.5 Mt @ 7.2% Zn, 1.3% Pb (St Marie and Kestler, 2000)

Pend Oreille mine proven + probable reserve - 4.7 Mt @ 7.0% Zn, 1.2% Pb (Teck Cominco, 2006)
    Inferred + indicated resource - 2.3 Mt @ 6.7% Zn, 1.3% Pb (Teck Cominco, 2006)

Operations recommenced in 2014, but the mine closed in 2019 after exhausting economic reserves.

For detail consult the reference(s) listed below.

The most recent source geological information used to prepare this decription was dated: 2020.     Record last updated: 24/9/2020
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:
Pannalal, S.J., Symons, D.T.A. and Leach, D.L.,  2007 - Paleomagnetic and mineral magnetic constraints on Zn-Pb ore genesis in the Pend Oreille Mine, Metaline district, Washington, USA : in    Can. J. Earth Sci.   v.44, pp. 1661-1673.
Paradis, S., Hnatyshin, D., Simandl, G.J. and Creaser, R.A.,  2020 - Re-Os pyrite geochronology of the Yellowhead-type mineralization, Pend Oreille Mine, Kootenay Arc, Metaline District, Washington: in    Econ. Geol.   v.115, pp. 1373-1384.
St Marie J, Kesler S E  2000 - Iron-rich and Iron-poor Mississippi Valley-type mineralization, Metaline district, Washington: in    Econ. Geol.   v95 pp 1091-1106

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, its employees and servants:   i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and   ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.

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