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Idaho Cobalt Belt - Blackbird, Ram, Sunshine, Blacktail, Black Pine, Salmon Canyon, Chicago, Merle, Brown Bear, Haynes-Stellite, Dandy, Iron Creek, Idaho |
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Idaho, USA |
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Co Cu
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
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The Blackbird, Sunshine and Ram cobalt deposits are near the centre of the 60 km long, up to 10 km wide, NW-SE oriented Idaho Cobalt Belt in central northeastern Idaho, within 50 km of, and parallel to, the border with Montana to the NE. The Blackbird mine is located 40 km west of the town of Salmon, ~175 km SW of Butte, Montana, and 230 km NE of Boise, Idaho, in western USA (#Location: 45°: 7' 35"N, 114° 21' 0"W). The Sunshine and Ram deposits are found to the north of and directly adjacent to the former Co-Cu producing Blackbird Mine. Ram is located ~1 km north of the Sunshine deposit. Other deposits/prospects in the belt include Blacktail, Brown Bear, Chicago, Dandy, Salmon Canyon, Iron Creek, Merle, Black Pine, Haynes-Stellite and Idaho.
NOTE: This summary comprises a general overview of the Idaho Cobalt Belt, focussed on the historic Blackbird mine, followed by descriptions of the Sunshine and Ram deposits which are the basis of the Idaho Cobalt Operations, which commenced operations in October, 2022.
Copper mineralisation was discovered in the Blackbird Creek area in 1892, leading to a search for copper and gold in the vicinity. The first mining in the area was undertaken by Union Carbide during World War I, at the Haynes-Stellite Mine, located to the immediate east of Blackbird. Approximately 3600 tonnes of cobalt bearing ore were treated before operations ceased. Between 1938 and 1941, the Uncle Sam Mining and Milling Company operated a mine at the south end of the present Blackbird mine and reportedly extracted ~3250 tonnes of ore. Calera Mining Company developed and mined the Blackbird deposit between
1943 and 1959 to supply cobalt to the US government, producing ~1.58 Mt @ 0.63% Co, 1.65% Cu, 1 g/t Au. Calera stopped mining when the government contract was terminated in 1960. Between 1963 and 1966, Machinery Center Inc. mined 0.310 Mt @ 0.36% Co, 0.64% Cu from the district, before the Idaho Mining Company, a subsidiary of Hanna Mining Company purchased the property. Noranda entered into an option agreement with Hanna in 1977, carried out extensive exploration, mine rehabilitation and metallurgical testing and in 1979 the two companies entered into a joint venture as the Blackbird Mining Company to develop the property. However, although a feasibility study was completed no further significant mining was undertaken. Between 1939 and 1968 2.574 Mt of ore had been mined. In 1994, the perimeter claims to the Blackbird property were allowed to lapse and were re-pegged Formation Capital Corporation who undertook a number of drilling programs that covered the Sunshine and Ram deposits with 120 diamond holes drilled between 1997 and 2017. In that period economic assessments were completed and mine construction commenced. In April 2019 the partially complete Idaho Cobalt Operations, which incorporates the Sunshine and Ram deposits, was purchased by Jervois Mining Limited. Having finalised construction, Jervois commenced commissioning in 2022, with full ore processing forecast by early 2023.
The mineral deposits of the Idaho Cobalt Belt lie within the broad, ~100 km wide, NE-SW oriented Great Falls tectonic zone, and are hosted within three NW-SE trending thrust fault-defined rock packages in the footwall of the regional-scale, Late Cretaceous Iron Lake Fault (Lund and Tysdal, 2007). These thrust slices are located within the southwestern section of the Mesoproterozoic Belt-Purcell basin, which is dominated by S-tectonites, in which metamorphic and planar fabrics were imparted during the Cretaceous (Sevier) Orogeny.
The three thrust slices comprise, from east to west, the lower (Haynes-Stellite), middle (Blackbird) and upper (Indian Creek) plates, composed respectively of i). middle greenschist facies biotite-phyllite and metasandstone; ii). pervasively foliated biotite-phyllite to schist at middle to upper greenschist facies; iii). distinctly layered, tightly folded, garnet-biotite gneiss and schist at upper greenschist to lower amphibolite facies grade. These rocks are interpreted to represent metamorphosed equivalents of the Yellowjacket, Apple Creek and Gunsight formations of the Ravalli, Piegan (or Middle Belt carbonate) and Missoula Groups respectively, of the Belt Supergroup.
Within the main Belt basin, the Belt-Purcell Supergroup consists of i). lower Belt formations, a southwest-derived deep-water turbidite wedge with locally abundant mafic sills, ii). the Ravalli Group, a largely sub-aerial, southwest-derived fluvial-deltaic complex, iii). the Piegan Group (Middle Belt carbonate), a cyclic carbonate and siliciclastic sequence of either lacustrine or marine setting, capped by a sequence of mafic to felsic lavas, and iv). the Missoula Group, a south- and east-derived fluvial succession (Winston and Link, 1993; Link et al., 2007; Winston, 2007). Most of the exposed stratigraphic section of the Belt-Purcell Supergroup was deposited between 1470 and 1400 Ma (Anderson and Davis, 1995; Evans et al., 2000). Intrusive rocks of Mesoproterozoic (porphyritic biotite granite and granodiorite), Neoproterozoic to Late Cambrian (including Cambrian syenite-diorite suites), Cretaceous (the extensive S-type Idaho Batholith granites) and Eocene age, outcrop within the district and surrounding region (Evans and Zartman, 1990; Tysdal et al., 2003; Lund et al., 2010).
Stratabound cobalt-copper deposits occur in the metasedimentary rocks of the Apple Creek Formation within the linear Idaho Cobalt Belt. The Apple Creek Formation generally comprises a thick sequence of metamorphosed argillite, siltite and quartzite with intercalations of biotite-rich layers interpreted to be formed from mafic tuffs. A large body of Mesoproterozoic granite, augen gneiss and mafic intrusive rocks (the 1380 to 1370 Ma Big Deer Creek pluton) occurs within 5 km to the north and east of the Blackbird Mine area. Several types of mafic dykes and sills, ranging from 1 to 30 m thick, intrude the Apple Creek Formation and are interpreted as feeders to the mafic tuffs, which are most abundant in areas of intrusive activity.
According to Nash, 1989, reported in Pegg, 1997), three types of cobalt-copper-gold occurrences have been reported hosted by the Apple Creek Formation in the Idaho Cobalt Belt:
• Type 1: Cobalt-copper-arsenic rich deposits of the Blackbird Mine type that generally contain approximately equal amounts of Co and Cu, with variable gold and pyrite. The dominant minerals include cobaltite (CoAsS) and chalcopyrite (CuFeS2). Cobaltite accounts for virtually all the As content in these occurrences. This mineralisation, which is tabular and stratabound, is closely associated with 'mafic sequences' within the Apple Creek Formation. Examples of this types of deposit include the Blackbird Mine and the mineralized zones found within Sunshine and Ram deposits.
• Type 2: Cobaltiferous-pyrite-magnetite deposits with variable chalcopyrite and low arsenic contents, hosted by fine-grained metasediments from the lower part of the Apple Creek Formation. Mineralization is stratabound and is found within syn-sedimentary soft sediment structures, and are located in the area of Iron Creek, ~27 km SE of the Blackbird Mine.
• Type 3: Cobaltiferous, tourmaline-cemented breccias, which are relatively common in the lower unit of the Apple Creek Formation, especially south and east of the Blackbird Mine. Only a few of these, apparently, contain more than 0.1% cobalt.
The Co-Cu mineralisation of the Blackbird Mine is predominantly hosted within the banded siltite unit of the Apple Creek Formation, locally extending into the underlying coarse siltite unit of the same formation and the overlying feldspathic quartzites of the basal Gunsight Formation (Lund and Tysdal, 2007). A gold-bearing layer occurs stratigraphically above the Co-Cu deposits, associated with metachert that has been interpreted to be siliceous tuff. Gold is also found within the Co-Cu ores of the Blackbird district (Nash et al., 1987).
Mineralisation, is overall stratabound and includes both conformable and vein-type orebodies. The major ore minerals are cobaltite and chalcopyrite, with minor pyrite, arsenopyrite, safflorite and pyrrhotite. Quartz, biotite, chlorite, muscovite, garnet, tourmaline, apatite and siderite are gangue minerals in the Blackbird deposit (Slack, 2007). There is a close association between cobalt-copper mineralisation and the occurrence of biotite-rich rocks, with the biotite-rich rocks interpreted to represent mafic tuffs by some authors (e.g., Nash and Hahn, 1987). High concentrations of REEs and yttrium are also recorded from the Idaho Cobalt Belt (Gillerman et al., 2000; Slack, 2006, 2007).
Both stratabound and vein-type mineralisation occurs at the Salmon Canyon prospect, hosted within upper amphibolite facies schists and gneisses of the Apple Creek Formation. Cobaltite mostly occurs as porphyroblasts within the coarse-grained stratbound ores in association with arsenopyrite. Chalcopyrite, pyrite, pyrrhotite and minor sphalerite are also present in the ores, which have been metamorphosed and remobilised (Nold, 1990). At the Black Pine prospect, which is located between the Iron Creek prospect and Blackbird deposit, mineralisation comprises bedded chalcopyrite with a variable cobaltiferous arsenopyrite content and minor cobaltite (Bending and Scales, 2001). There are two mineralised zones at the Iron Creek prospect, i). a lower magnetite-rich, and ii). an upper sulphide-rich (cobaltiferous pyrite and chalcopyrite) zone. Two generations of pyrite have been recognised: the fine-grained stratiform and the coarse-grained epigenetic varieties. Most of the cobalt is contained within the epigenetic variety of pyrite (Nash, 1989a).
Deposits within the Blackbird district are intrafolial concordant layers and lenses in schist and gneiss and discordant lenses in metamorphosed siliciclastic rocks of the Apple Creek Formation. Several of these sulphide deposits (e.g., Dandy) are discordant to metamorphic layers, forming vein-type structures (Lund et al., 2011). Elsewhere within the district, (e.g., Haynes-Stellite deposit), discordant tourmalinised breccia bodies contain abundant cobaltite and xenotime (Lund et al., 2011; Slack, 2012). The sulphide-rich deposits, concordant to metamorphic layering, vary from <1 to 4 m thick and mainly comprise cobaltite and chalcopyrite in a gangue of Fe-rich biotite with lesser quartz, chlorite, garnet, chloritoid, tourmaline and/or muscovite (Anderson, 1947; Purdue, 1975; Modreski, 1985; Nash and Hahn, 1989). The Sunshine deposit (described in more detail below) differs in having a quartz-rich gangue with minor chlorite (Eiseman, 1988). Rare magnetite is generally a minor constituent, but is locally abundant in several small deposits and prospects (Slack, 2012). Other ore minerals include pyrite, pyrrhotite, arsenopyrite, glaucodot, safflorite, bismuthinite, native Bi, Bi tellurides and gold. Very high Bi contents of >1 wt.% are locally present, including 9.2 wt.% in a Cu-rich sample from the Ram deposit. Sparse uraninite, sphalerite, stannite and an unidentified Bi selenide are also present (Slack, 2012), while some of the sulphide deposits, e.g., Sunshine, Merle, Brown Bear and Ram, contain minor to abundant allanite, apatite, xenotime, and/or monazite (Slack, 2006).
Aleinikoff et al. (2012) present data they interpret to indicate i). the host sedimentary rocks to the mineralisation were deposted between 1409±10 and ~1370 Ma, ii). granitoid plutons in the district were emplaced between 1383±4 and 1359±7 Ma and may be related to the first phase of the REE, Co-Cu and Au mineralisation, iii). Cretaceous xenotime, monazite and associated cobaltite formed in multiple phases that are interpreted as remobilised and reprecipitated Mesoproterozoic sulphide ore during Middle to Late Cretaceous metamorphic events.
Production in the Blackbird district commenced in 1917, after the initial discovery of sulphide mineralisationin 1893, with minor Co being removed from the Haynes-Stellite Mine between 1917 and 1920 (Bennett, 1977). Major production began in 1949 and continued intermittently until 1960 at the Blackbird (Uncle Sam) underground mine and the Blacktail open pit, together producing ~5 Mt @ 1.5 wt.% Cu, 0.6 wt.% Co (Nash and Hahn, 1989; Bending and Scales, 2001).
Bennett (1977) used Hanna Mining Co.data to calculate unmined reserves for the Blacktail, Brown Bear, Chicago, Dandy and Idaho deposits at 5.9 Mt @ 1.31 wt.% Cu, 0.55 wt.% Co.
Formation Metals Inc. (2009; 2012) reported a total resource for four deposits of:
11.7 Mt @ 0.7 wt.% Co, 1.1 wt.% Cu, including:
The Ram deposit, which has,
proven, probable and diluted reserves, (0.2% Co cut-off), of 2.64 Mt @ 0.56 wt.% Co, 0.60 wt.% Cu, 0.4 g/t Au, plus,
inferred resource of 1.12 Mt @ 0.59 wt.% Co, 0.79 wt.% Cu, 0.53 g/t Au.
The Black Pine deposit (~15 km SE of Blackbird) has a small sulphide resource of:
1.0 Mt @ 4.5 wt.% Cu, 0.08 wt.% Co, 1.03 g/t Au (Johnson et al., 1998).
Slack et al., 2012) indicates that past production + reserves and resources in 14 deposits of the Blackbird district, excluding Black Pine, total:
16.8 Mt @ 0.74 wt.% Co, 1.37 wt.% Cu, 1.04 g/t Au.
Idaho Cobalt Operations
The Idaho Cobalt Belt is hosted within strata of the Mesoproterozoic Apple Creek Formation, which is an upward coarsening clastic sequence that is at least 15 000 m thick (Nash, 1989), representing a major basin-filling episode (Connor, 1990) and is considered part of the Yellow Jacket Formation of the Belt Supergroup, as detailed above.
Ram Deposit
The stratigraphy in the Ram deposit area is predominantly composed of medium- to fine-grained meta-greywacke (previously described as quartzite)that has been metamorphosed to upper greenschist to amphibolite facies. The Ram deposit stratigraphy has been split into the:
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• Footwall Zone - which comprises two rock packages, the upper footwall characterised by poorly to well-bedded silty quartzite to meta-greywacke, often intercalated with chloritic and biotitic lenses, and the lower footwall which frequently contains distorted bedding due to soft sediment deformation but lacks chloritic and biotitic lenses.
• Main Zone - dominated by fine- to medium-grained, thin- to medium-bedded metagreywackes that are interbedded with biotite and chlorite-rich horizons, and locally silicified lenses, previously interpreted as siliceous tuffaceous exhalites. Mineralisation in this zone is generally found within a confined stratigraphic package containing up to three, closely spaced, stratabound biotite and chlorite-rich horizons of variable thickness and continuity, which strike between 340 and 355° and dip between 50 and 55°NE. The main mineralised zone varies from ~4.5, up to 24 m in some areas, although the Co mineralisation is restricted to the heavily biotitic/chloritic lenses, where a single lense will rarely exceed 3 m in thickness, with more frequent shoulders of lower grades. The Main zone biotitic/chloritic lenses contain fine- to coarse-grained disseminations, bands, blebs and stringers of cobaltite, chalcopyrite and minor pyrite. This mineralisation is dominantly concordant with bedding but is locally cut by thin quartz veins or crosscutting structures. The main zone represents the bulk of the potentially economic mineralisation identified in the Ram deposit to date.
• Hanging wall Zone - which has, in turn, been subdivided into three similar and gradational lithological packages, the:
- Lower hanging wall, which includes medium- to coarse-grained metagreywacke with poorly defined, chaotic bedding. Biotitic/chloritic material is restricted to sporadic, irregular interbedded lenses. The chaotic bedding is interpreted to be soft sediment deformation structures with load textures, small scale slump structures and deformed lamination.
- Middle hanging wall, dominated by medium-grained, generally well-bedded meta-greywacke that is locally conformably interbedded with chloritic/biotitic cobaltiferous horizons.
- Upper hanging wall, which contains medium- to coarse-grained, locally poorly bedded to well-bedded meta-greywacke. Occurrence of biotite-rich interbeds is generally restricted to discontinuous, irregular coarse-grained garnetiferous pods.
The current resource model contains six chloritic/biotitic-rich horizons that occur in between the three hanging wall zones. Each has limited interpreted spatial extent, which may be due to the soft sediment deformation obscuring the lateral continuity of such horizons.
Faulting/Structures - seven major faults and five minor splays have been identified in the Ram deposit area, some of which continue to the south and match previous structures mapped at the Blackbird deposit. In the Ram deposit, a north-trending vertical to steeply west-dipping normal fault cuts the main zone in the south near the centre of the deposit and diverges to the North. Two other parallel and semi-vertical faults also cut the main zone with predominantly normal to normal oblique displacements, with the strongest displacements near the south of the deposit. Two NE-SW trending semi-vertical faults occur near the southern and northern ends of the main zone with a stronger strike-slip component than the more predominant north-south faults. Minor faults or splays are structures that may not have significant displacement but do produce strongly fractured and brecciated zones.
Soft sediment deformation predominates near the centre of the deposit and it appears to affect some of the hanging wall horizons strongly. Irregular laminations and flame structures are seen in drill core, likely representing deposit scale slump structures that affect the lateral continuity of some of the stratigraphic horizons.
Mineralisation occurs in the Hanging wall Zone with six minor, somewhat discontinuous horizons; the Main Zone, as of up to three chloritic/biotitic-rich horizons, and a Footwall Zone that is somewhat discontinuously developed. Most of the significant Co mineralisation is associated with heavily biotitic-chloritic altered interlayered horizons that are somewhat silicified and locally brecciated, and metagreywacke with interlayered biotitic or siliceous horizons.
Sunshine Deposit
The stratigraphy at the Sunshine deposit, including the chloritic/biotitic horizons, as described in the Ram section above, strikes NNE and dips moderately to steeply to the ENE. Whilst individual sulphide-bearing beds may not be continuous over distances of more than a hundred metres, the overall mineralised zones containing chloritic/biotitic horizons can be traced along strike lengths of >500 m.
• The Footwall Zone stratigraphy is dominated by a thick sequence of monotonous siltite or pelite with minor interbedded sandy units. Mafic sequences, characterised by green biotite and lesser chlorite, are rare and can only be correlated locally. Shearing is prevalent within this package. The boundary between the footwall and the main zone is defined by a sedimentary interface based on grain size, indicating a change from deeper to shallower water.
• The Main Zone at Sunshine is composed of fine- to medium-grained meta-quartzite interbedded with siltite and Mafic sequences. The Mafic sequences comprise green biotite and lesser chlorite, interpreted to be metamorphosed tuffs (Clark, 1995). Portions of this sequence contain significant amounts of concordant cherts (Clark, 1995).
• The Hanging wall Zone stratigraphy is dominated by upward coarsening and thickening quartzite. In the lower hanging wall, quartzite is locally intercalated with siltite and minor mafic sequences, while in the upper hanging wall quartzite contains little siltite and no mafic sequences.
Discontinuous concordant to sub-concordant quartz veins occur throughout the Sunshine Lode’s stratigraphy. These are interpreted to be of diagenetic origin, and while they are occasionally mineralised, they are not traceable for any significant length either along strike or down dip.
Folding, at least locally and on the bedding scale, is evident in drill core and may be consistent with the suggestion that folded repetitions of the ore units occur, although no definitive evidence has been documented.
Mineralisation at Sunshine appears to be cut by several discontinuous, shallow to moderate, west-dipping, dip-slip faults/shears, as well as several discontinuous, crosscutting tectonic breccias, possibly affecting the continuity of the lode, at least locally.
The mineralised zone at Sunshine occurs within a confined stratigraphic interval that contains a main mineralised horizon, a lower footwall horizon, and an upper hanging wall horizon. Whilst the mineralised zone is continuous along strike, the individual horizons do not always have good continuity either along strike or down dip. The footwall and hanging wall horizons attenuate rapidly both along strike and down dip, although, within the main and hanging wall horizons, tabular deposits of mineralisation with sufficient grade and size exist, which are considered to be mineable. These deposits appear to have a north-plunging long axis.
The stratabound mineralisation occurs as fine- to medium-grained disseminations, blebs and stringers of cobaltite and minor chalcopyrite and pyrite. Two types of mineralisation are found within the Sunshine Lode, i). fine- to coarse-grained cobaltite within a siliceous gangue and ii). fine-grained cobaltite within micaceous gangue of black and green biotite, and chlorite. The mineralised horizons are typically composed of both mineralisation types and are hosted by medium-grained biotite rich quartzites.
The mineralised zones at the Sunshine deposit are stacked sulphide-bearing beds. Individual mineralised beds/horizons are intimately associated with biotite-rich horizons. An increase in silica content generally indicates an increase in cobalt, copper and gold grades.
Alteration
The Apple Creek Formation has been subjected to varying degrees of regional metamorphism, which grades from greenschist facies in the south of the district to dominantly amphibolite grade facies in the north. The alteration pattern is superimposed upon the varying metamorphic assemblages. On a broad scale, mineralisation related alteration is manifested by tourmaline and ankerite in the host central unit, although these alteration minerals can also be found up to a thousand metres from the nearest known sulphide occurrences, and thus, do not necessarily provide any reliable vector to mineralisation. Locally, ankerite grades into disseminated siderite. Silicification and chloritisation have been noted within the mineralised zones, although similarly chlorite-rich rocks may be found as much as ~100 m from known mineralisation. The chloritic/biotitic-rich horizons associated with mineralisation have been interpreted to represent hydrothermally altered meta-argillites, at least near the Ram deposit, where no evidence of co-existing volcanism has been seen. Alteration at Ram and Sunshine is similar to that found at the Blackbird deposits which have been described as being strata-bound and coincident with biotite and intercalated rocks with the alteration zoning consisting of pyrite-siderite-quartz-muscovite in the core zone, grading outward into quartz-muscovite with lesser pyrite.
Mineralisation
Mineralisation at Ram and Sunshine is of the Type 1 of Nash (1989), as reported in Pegg (1997) as detailed above. They are characterised as stratabound/tabular deposits, although associated mafic sequences have not been unequivocally identified to date. Mineralisation is dominantly bedding concordant, with the deposits ranging from nearly massive to disseminated sulphides, although some crosscutting mineralisation is present, occurring locally in fracture quartz veins and/or crosscutting structures.
The dominant minerals include cobaltite (CoAsS) and chalcopyrite. Other minerals found in small amounts are pyrite, pyrrhotite, arsenopyrite, linnaeite ((Co Ni)3S4), loellingite (FeAs2), safflorite (CoFeAs2), enargite (Cu3AsS4), and marcasite.
Rare-earth minerals have been identified in samples from the deposit as monazite, xenotime and allanite, although not at sufficient grades to be economically extracted as by-products.
Reserves and Resources
NI 43-101 compliant Ore Reserves and Mineral Resources as of November 2020 (Sletten, et al., 2020) were:
NOTE: Reserves are at a 0.24% Co payable equivalent cut-off.
Proved Reserve - 1.44 Mt @ 0.63% Co, 0.67% Cu, 0.53 g/t Au;
Probable Reserve - 1.05 Mt @ 0.53% Co, 0.96% Cu, 0.80 g/t Au;
Proved + Probable Reserve - 2.49 Mt @ 0.55% Co, 0.80% Cu, 0.64 g/t Au.
Measured Resource - 2.65 Mt @ 0.45% Co, 0.59% Cu, 0.45 g/t Au;
Indicated Resource - 2.59 Mt @ 0.42% Co, 0.80% Cu, 0.62 g/t Au;
Measured + Indicated Resource - 5.24 Mt @ 0.44% Co, 0.69% Cu, 0.53 g/t Au;
Inferred Resource - 1.57 Mt @ 0.35% Co, 0.44% Cu, 0.45 g/t Au.
The information in the Idaho Cobalt Operations section is largely drawn from Sletten, M., Zelligan, S., Frost, D., Yugo, N., Charbonneau,, C. and Cameron, D.P., 2020 - Idaho Cobalt Operations, Form 43-101F1 Technical Report, Feasibility Study Idaho, USA; prepared by M3 Engineering and Technology Corporation for Jervois Mining Limited, 416p.
The most recent source geological information used to prepare this decription was dated: 2020.
Record last updated: 14/10/2022
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.
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Aleinikoff J N, Slack J F, Lund K, Evans K V, Fanning C M, Mazdab F K, Wooden J L and Pillers R M, 2012 - Constraints on the Timing of Co-Cu ± Au Mineralization in the Blackbird District, Idaho, Using SHRIMP U-Pb Ages of Monazite and Xenotime Plus Zircon Ages of Related Mesoproterozoic Orthogneisses and Metasedimentary Rocks : in Econ. Geol. v.107 pp. 1143-1175
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Johnson C A, Bookstrom A A and Slack J F, 2012 - Sulfur, Carbon, Hydrogen, and Oxygen Isotope Geochemistry of the Idaho Cobalt Belt: in Econ. Geol. v.107 pp. 1207-1221
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Landis G P and Hofstra A H, 2012 - Ore Genesis Constraints on the Idaho Cobalt Belt from Fluid Inclusion Gas, Noble Gas Isotope, and Ion Ratio Analyses : in Econ. Geol. v.107 pp. 1189-1205
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Lund K, Tysdal R G, Evans K V, Kunk M J and Pillers R M, 2011 - Structural Controls and Evolution of Gold-, Silver-, and REE-Bearing Copper-Cobalt Ore Deposits, Blackbird District, East-Central Idaho: Epigenetic Origins : in Econ. Geol. v.106 pp. 585-618
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