Mineralization at the Polaris Mine, Idaho

Willard, Max E.

doi:10.2113/gsecongeo.36.5.539

Cited by 5 publications

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“…At the Sunshine Mine, galena ore shoots are superimposed on pre-existing fahlore shoots, and only where those fahlore shoots are also coincident with major faults. In microscopic examination of textures, the bournonite is described as replacing fahlore (Rasor, 1934;Willard, 1941), and as ''a reaction product representing an intermediate stage in the replacement of tetrahedrite by galena'' (Anderson, 1940, p. 665). Fryklund (1964, p. 18), however, notes that bournonite ''also occurs as veinlets in galena away from tetrahedrite contacts''.…”

Section: Discussionmentioning

confidence: 99%

Retrograde Ag-enrichment in fahlores from the Coeur d'Alene mining district, Idaho, USA

Sack

Kuehner

Hardy³

2002

Mineral. mag.

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Tetrahedrite fahlores from the Coeur d'Alene mining district (Idaho) have been found to be enriched in Ag by the Ag Cu exchange reaction 1 10 Cu 10 (Zn,Fe) 2 Sb 4 S 13 + AgSbS 2 + PbS = CuPbSbS 3 + 1 10 Ag 10 (Zn,Fe) 2 Sb 4 S 13 Cu-fahlore in galena galena bournonite Ag-fahlore which occurred during cooling following galena mineralization. This solid state reaction resulted in quantitative removal of Ag (in a AgSbS 2 component) from galena and development of bournonite coronas on fahlore grains. The reaction produced a distinct population of high-Ag fahlores found in galena-rich samples and accounts for all of the bournonite mineralization. The most argentian of these high-Ag fahlores examined in this study (molar Ag/(Ag+Cu) = 0.303+0.011 and 0.336+0.011) are found in samples which achieved saturation with respect to other Ag-sulfosalts, namely pyrargyrite and polybasite and diaphorite, respectively. Multiple lines of evidence for the Ag-Cu exchange reaction are presented in this paper which applies mass-balance constraints and a thermodynamic database for sulfides/sulfosalts to microprobe analyses and textural observations, and to bulk production data. This solid-state reaction may explain why previous district studies have been unable to demonstrate convincingly primary fahlore zoning. Based on the Ag/(Ag+Cu) of fahlores coexisting with other Agsulfosalts and Fe-Zn partitioning between fahlore and sphalerite, we estimate that fahlore compositions were frozen in by 1758C. Examining the composition data for other Ag tetrahedrite fahlores found in the Coeur d'Alene district and elsewhere, we conclude that the thermodynamic database provides an accurate description of phase equilibria, except possibly for very Fe-rich systems where further studies of the Fe-Zn partitioning between fahlore and Fe-rich (Zn,Fe)S phases and of the thermodynamics of Fe-rich (Zn,Fe)S phases are warranted.

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Section: Discussionmentioning

confidence: 99%

Retrograde Ag-enrichment in fahlores from the Coeur d'Alene mining district, Idaho, USA

Sack

Kuehner

Hardy³

2002

Mineral. mag.

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“…The Polaris ore shoot is on the Sunshine B vein. Willard (1941). This network of west-to north-striking veins links the Chester and Sunshine B veins.…”

Section: Coeur D'alenementioning

confidence: 92%

Ore deposits of the Coeur d'Alene district, Shoshone County, Idaho

Fryklund¹,

Weis²

1964

Professional Paper

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The Coeur d'Alene district of this report is that area in northern Idaho between the Montana State line and longitude 116°17', and between latitudes 47°26'15" and 47°33'45".The country rock of the area consists of the Prichard, Burke, Revett, St. Regis, Wallace, and Striped Peak Formations of the Precambrian Belt Series. These formations are composed of fine-grained quartz-rich rocks that have been mildly regionally metamorphosed and which, in conse• quence now belong to the green schist facies. The ubiquitous sericite was oriented during the folding and metamorphism and the rocks now consist of quartzose slate, sericite phyllite, sericite quartzite, and in a few areas, schistose quartzite and sericite schist.Igneous rocks of the area include monzonite stocks and related monzonite dikes, which were probably intruded at the same time as the Idaho batholith, and biotite lamprophyre, diabase, and porphyritic hornblende-augite-olivine-dikes, the latter perhaps varieties of the diabase dikes. The two stocks are part of a line of northeastward-striking intrusives that apparently lie along a major fracture. This fracture is probably one of the controlling factors in the origin of the Coeur d'Alene district.Several sets of faults can be recognized; there is no certainty that any are older than the shear zones that contain ore deposits, but the great strike-slip faults-the Osburn and Placer Creek faults-have offset mineral belts.Idaho, within which the Coeur d'Alene district is the only important mining area, has ranked second in lead and in zinc production for many years. The first recorded production from the Coeur d'Alene district proper was

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Bibliography to Data Section

Dub

1962

Organometallic Compounds

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Mineralization at the Polaris Mine, Idaho

Cited by 5 publications

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Retrograde Ag-enrichment in fahlores from the Coeur d'Alene mining district, Idaho, USA

Retrograde Ag-enrichment in fahlores from the Coeur d'Alene mining district, Idaho, USA

Ore deposits of the Coeur d'Alene district, Shoshone County, Idaho

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