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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  05-Jun-1991 by Dorthe E. Jakobsen (DEJ)

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NMI
Name BOBBI, MARY, ELEANOR 1-8, KIM 1-8, BOBBI 2-5, MURIEL 1-4, BETTY 2-4, ALABAMA (L.2279), ATLANTA (L.2280) Mining Division Nelson
BCGS Map 082F024
Status Showing NTS Map 082F06E
Latitude 049º 17' 50'' UTM 11 (NAD 83)
Longitude 117º 14' 35'' Northing 5460526
Easting 482328
Commodities Molybdenum, Tungsten, Copper, Fluorite, Gold, Lead, Zinc Deposit Types L03 : Alkalic porphyry Cu-Au
L07 : Porphyry W
I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Omineca Terrane Quesnel, Plutonic Rocks
Capsule Geology

The Bobbi showing is located 2 kilometres northwest of Ymir. The Bobbi and Stewart 2 (082FSW229) occurrences are the most significant porphyry showings in the Nelson-Ymir area. Numerous small pits and adits occur on the property mainly from tungsten exploration carried out on the Alabama and Atlanta Crown Grants.

The area, on the east limb of a north trending syncline, is underlain by sediments of the Hall Formation and volcanic rocks of the Elise Formation (unit Je11) both of the Lower Jurassic Rossland Group (Open File 1989-11). The Hall Formation sediments consist of a sequence of argillite, shale, siltstone and sandstone. The volcanic rocks are primarily tuffaceous conglomerates but andesite, flow breccia, tuff and augite porphyry are present to the east. These are intruded by quartz monzonite to quartz diorite plugs and dykes of the Late to Middle Jurassic Nelson Intrusions and Tertiary rhyolite dykes.

The most common intrusion is an albite porphyry of quartz diorite composition. Other intrusions include plagioclase porphyry and quartz monzonite. The quartz monzonite is a medium-grained, light grey to white coloured plug which contains phenocrysts up to 1.5 centimetres in length of quartz, feldspar, biotite and hornblende.

Molybdenite, scheelite and minor chalcopyrite are found along with sericite in quartz veins and in fractures within the quartz monzonite plug. Fluorite is a common accessory mineral within the intrusive. Low lead and zinc values were noted from Hall sediments near the intrusive margin. Pyrite is ubiquitous in both sediments and volcanics and disseminated pyrrhotite and minor chalcopyrite are hosted in Hall sediments. Prospecting indicated very minor disseminated chalcopyrite, sphalerite and galena in quartzitic sediments. No anomalous silver, gold or tin values were reported. Reported radioactivity is due to the presence of potassium feldspar within the quartz porphyry intrusive.

A sample from trench 6 in 1980 assayed 0.07 per cent copper, 0.115 per cent molybdenite, 0.03 per cent Wo3 and less than 0.1 grams per tonne gold with 0.078 per cent fluorine (Assessment Report 8448).

Bibliography
EMPR ASS RPT 2301, 6654, 7656, 8017, *8448, 11670, 13166
EMPR BULL 9; 10 (Rev); 41; 109
EMPR EXPL 1979-63; *1980-62
EMPR FIELDWORK 1980, pp. 149-158; 1981, pp. 28-32, pp. 176-186; 1987, pp. 19-30; 1988, pp. 33-43; 1989, pp. 247-249; 1990, pp. 291-300
EMPR MAP 7685G; RGS 1977; 8480G
EMPR OF 1988-1; *1989-11; 1991-16; 1991-17; 1992-16
GSC MAP 50-13A; 50-19A; 1090A; 1144A
GSC MEM 77; 172; 308
GSC P 49-22; 50-13; 51-4
Andrew, K.P.E. and Hoy, T. (1990): Structural Models for Precious Metal Deposits in Jurassic Arc Volcanic rocks of the Rossland Group, southeastern B.C.; abstract with program, G.A.C. - M.A.C. Annual Meeting, Vancouver, B.C., p. A3
Hoy, T. and Andrew, K.P.E. (1988): Geology, geochemistry and mineral deposits of the Lower Jurassic Rossland Group, southeastern British Columbia; abstract in Twelfth District 6 Meeting, Canadian Institute of Mining and Metallurgy, Fernie, B.C., pp. 11-12

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