Occurrence Details


Occurrence Number:
105M 018
Occurrence Name:
Formo Mine
Occurrence Type:
Hard-rock
Status:
Deposit
Date printed:
4/29/2025 3:13:39 AM

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General Information
Capsule
Work History
Assessment Reports
References
Resource / Reserve

General Information

Primary Commodities: lead, silver, zinc
Aliases: Yukeno
Deposit Type(s): Vein Polymetallic Ag-Pb-Zn+/-Au
Location(s): 63°56'14" N - -135°22'1" W
NTS Mapsheet(s): 105M14
Location Comments: Location coordinates provided by Alexco
Hand Samples Available: No
Last Reviewed:

Capsule

Work History

Staked as Dorothy (38807) and Rocket cl (14457) in Dec/21 by G. Gray and D. Horne and as Tyee cl (16038) and Rocket cl (16575) in Jul-Sep/25 by H.E. Formo and A. Stewart. Formo explored both claims with shafts and drifts from 1929-31 when 36.3 tonnes of ore were shipped. The claims were taken to lease (Lots 273 and 274) in Sep/34 and renewed in Sep/55.

Silver Basin Mines Ltd optioned the property in 1947, shipped 54.4 tonnes of ore later in the year, and purchased the claims in Nov/48. The claims were transferred in Jan/50 to Consolidated Yukeno Mines Ltd and in Feb/51 to Yukeno Mines Ltd, which carried out underground development in 1952-53. Over 1 219.2 m of drifting and crosscutting, plus minor raising and shaft sinking, were completed on three levels.

A.A. Smith leased the property in 1961 and shipped 13.4 tonnes of ore. In 1962, the property was purchased by Rio Plata Silver Mines Ltd, which explored with 13 x-ray holes (205.1 m) and bulldozer trenching in 1964; more trenching, EM surveying, underground rehabilitation and drilled 8 holes (274.3 m) in 1974; and percussion drilling in 1975.

During this period A.D. Ross restaked the Something cl fr (Y84831) in Aug/73, which was a relocation of a former surveyed mineral claim of the same name located immediately south of the Dorothy claim. In the autumn of 1973 Rio Plata carried out magnetometer surveying and geochemical soil sampling of the Formo property including the Something cl fr which had been earlier acquired form Ross. Ross also staked the Ross cl (Y85975) 2 km to the south in Oct/73 and after acquiring this claim (part of their Aztec group) Rio Plata carried out geochemical soil sampling of the claim in 1973 and 1975.

In 1980-81, the 2 700 level adit was rehabilitated and the southerly extension was explored with 54 percussion holes (2 647.2 m) and 6 core holes (289.6 m). The property was leased in Feb/82 to J.B. O'Neill, who mined about 71.7 tonnes of ore in 1983.
In Apr/83, the Rocket claims were transferred to Reflection Resources Ltd. The adjacent Rex, Pro, Abel, Cain (YCML 1044) and Horseshoe claims to the west were acquired in Feb/80 by Canada Tungsten Mining Corporation Ltd, which carried out geochemical soil sampling, before transferring the claims to Springmount Operating Company Ltd in May/87.

In Jun/86, all of Rio Plata's claims in the district were optioned to Dawson Eldorado Mines Ltd which carried out trenching later in the year.

Silver Quest Resources acquired 13 mining leases over and surrounding the original occurrence. Surface samples of mine materials were assayed to confirm historical values.

Capsule Geology

Erratic narrow lenses of galena, sphalerite and minor tetrahedrite occur in carbonate gangue within a typical narrow, north-trending, transverse vein cutting schist and greenstone beneath the Keno Hill Quartzite. The 1973 trenching explored a 213 m interval along the structure and is said to have exposed a mineralized zone 45.7 m long grading from 2 057.1 to 3 257.1 g/t Ag across a 1.2 m width.

The 1975 percussion drilling located a new vein 180 m northwest of the main vein. Formo's 1931 shipment graded approximately 7 886 g/t Ag Ag and 60% Pb. The 1961 shipment graded 4 957.6 g/t Ag, 57% Pb and 10.3% Zn. Campbell estimated proven and probable ore reserves in 1965 at 39 917 tonnes grading 548.6 g/t Ag, 6.9% Pb and 10.7% Zn but regarded this estimate as optimistic, a similar figure of 40 000 tonnes grading 550 g/t Ag, 6.9 % Pb and 10.7% Zn was reported in 1989 (Morin, 1989).

The 1980-81 drill program showed that mineralization is restricted to the Formo showing and failed to locate any new ore missed in the underground workings. The best intersection assayed 2290.2 g/t Ag and 1.0 g/t over 48 cm. Erratic gold values up to 17.1 g/t were obtained from a few of the vein intersections. O'Neill mined a 90 cm wide lens of galena near the 1930 shaft and the first 48 tonnes of his shipment graded 4909.6 g/t Ag, 57.4% Pb and 9.6% Zn.

Sampling of the old mine dump on the property by Silver Quest Resources in 2009 confirmed historical values with rock assay results of 3025 g/t Ag, 0.096% Cu, 15.85% Pb and 39.80% Zn.

References

CANADIAN MINING JOURNAL, Feb/50, p. 80.

DAWSON ELDORADO MINES LTD, Feb/87. Assessment Report #092159 by P.D. Van Angeren and P.S. White.

GEOLOGICAL SURVEY OF CANADA Bulletin 111, p. 21-22.

GEOLOGICAL SURVEY OF CANADA Paper 62-27, p. 27; 63-38, p. 10.

GEORGE CROSS NEWSLETTER, 24 Sep/73; 24 Dec/75.

MINERAL INDUSTRY REPORT 1974, p. 12-13.

MORIN, J.A., 1989. Yukon Gold-Silver File. Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Open File 1989-3.

MURPHY, D.C. and ROOTS, C.F., 1996. Geological map of Keno Hill area, Central Yukon (105M/14). Exploration and Geological Services Division, Indian and Northern Affairs Canada, Geoscience Map 1996-5, scale-1:50 000.

MURPHY, D.C., 1997. Geology of the McQuesten River Region, Northern McQuesten and Mayo Map Areas, Yukon Territory (115P/14, 15,16; 105M/13, 14). Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Bulletin 6, 122 p.

RIO PLATA SILVER MINES LTD, May/75. Assessment Report *#061269 by K.L. Daughtry.

RIO PLATA SILVER MINES LTD, May/75. Assessment Report *#061270 by K.L. Daughtry.

RIO PLATA SILVER MINES LTD, 1975. Assessment Report *#090063 by K.L. Daughtry.

RIO PLATA SILVER MINES LTD, Jan/76. Assessment Report *#090064 by K.L. Daughtry.

ROOTS, C.F., 1997. Bedrock geology of Mayo map area, central Yukon (105M). Exploration and Geological Services Division, Indian and Northern Affairs Canada, Geoscience Map 1997-1, 1:50 000-scale.

ROOTS, C.F., 1997. Geology of the Mayo Map Area, Yukon Territory (105M). Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Bulletin 7, 82 p.

SILVER QUEST RESOURCES LTD., News Release, 17 Jun/09.

YUKON EXPLORATION 1988, p. 122-124.

YUKON EXPLORATION AND GEOLOGY 1981, p. 167.

 

Work History

Date Work Type Comment
12/31/2009 Geochemistry
12/31/1983 Development, Underground Mined 71.7 t of ore.
12/31/1981 Drilling Six holes, 289.6 m.
12/31/1981 Drilling Fifty-four holes, 2,647.2 m.
12/31/1981 Development, Underground
12/31/1980 Development, Underground
12/31/1975 Drilling
12/31/1974 Drilling Eight holes, 274.3 m.
12/31/1974 Development, Underground
12/31/1974 Ground Geophysics
12/31/1974 Trenching
12/31/1964 Drilling Thirteen holes, 205.1 m. X-ray size holes.
12/31/1964 Trenching
12/31/1961 Development, Underground Sipped 13.4 t of ore. Mining performed by A.A. Smith.
12/31/1953 Development, Underground Drifting and crosscutting, plus minor raising and shaft sinking.
12/31/1952 Development, Underground Drifting and crosscutting, plus minor raising and shaft sinking, approximately 1,219.2 m.
12/31/1947 Development, Underground Shipped 54.4 t of ore.
12/31/1931 Development, Underground Shipped 36.3 t of ore.
12/13/2008 Geochemistry
12/13/2008 Geochemistry
12/13/2008 Geochemistry
12/13/2006 Airphotography
12/13/2006 Airphotography
12/13/2006 Airborne Geophysics
12/13/2006 Airborne Geophysics
12/13/2006 Pre-existing Data
12/13/2006 Remote Sensing
12/13/1986 Lab Work/Physical Studies
12/13/1986 Geochemistry
12/13/1986 Geochemistry
12/13/1986 Pre-existing Data
12/13/1986 Trenching
12/13/1986 Geology
12/13/1986 Other
12/13/1970 Airborne Geophysics
12/13/1925 Geology
12/13/1925 Studies

Assessment Reports that overlap occurrence

Report Number Year Title Worktypes Holes Drilled Meters Drilled
096732 2014 Assessment Report Describing Metallurgical Test Pits, Metallurgical Auger Drilling, Geotechnical Auger Drilling, Geotechnical Study, Environmental Baseline Studies, Heritage Evaluation, and Water Quality and Climate Monitoring Surveys Auger - Drilling, Water - Geochemistry, Metallurgical Tests - Lab Work/Physical Studies, Environmental Assessment/Impact - Studies, Geotechnical - Studies, Heritage/Archeological - Studies 9 96.77
095661 2008 2008 Geological, Geochemical and XRF Assessment Report on the Keno Hill Property Biogeochemistry - Geochemistry, Rock - Geochemistry, Soil - Geochemistry
094943 2006 2006 Geological, Aerial Photography and Orthophoto Assessment Report on the Keno Hill Property Electromagnetic - Airborne Geophysics, Magnetic - Airborne Geophysics, Interpretation - Airphotography, Orthophoto - Airphotography, Digitizing Data - Pre-existing Data, Photogrammetry - Remote Sensing
090564 1979 Geological, Geochemical, and Geophysical Report Rock - Geochemistry, Silt - Geochemistry, Soil - Geochemistry, Bedrock Mapping - Geology, EM - Ground Geophysics, Seismic - Ground Geophysics, Research/Summarize - Pre-existing Data
060942 1970 Report on Aeromagnetic Survey-Keno Area, Yukon Territory Magnetic - Airborne Geophysics
019927 1925 [Galena Hill-Geological Map-Hector Mine Sections and Block Diagrams] Bedrock Mapping - Geology, Geotechnical - Studies

Related References

Number Title Page(s) Reference Type Document Type
ARMC014843 Zones being explored on Galena Hill property Property File Collection Geoscience Map (General)
ARMC014848 Plan of Comstock Vein - Gold Hill No. 2 - Galena Hill, Yukon Territory - Plate VI Property File Collection Geoscience Map (General)
ARMC014849 Plan of detailed sampling - Formo shaft area - Galena Hill, Yukon Territory - Figure 2 Property File Collection Geoscience Map (General)
ARMC014862 Plan of survey of Premier, Dorothy, Tagish, Skookum, Cheechako, Papoose, Bra, Birch, Spruce Tillicum, Something Fr. & Wimpy Fr. mineral claims - Situated on the north-east slope of Galena Hill in the Mayo mining district Property File Collection Geoscience Map (General)
ARMC014860 Report on Rio Plata Silver Mines Limited - 1964 operations and development Property File Collection Report
ARMC014856 Property submission - Rose Zeniuk - Keno Hill area Property File Collection Report
ARMC014858 Prospectus - Rio Plata Silver Mines Ltd. (N.P.L.) - Including reports on the Formo and Haggert Creek claim groups Property File Collection Report
ARMC014859 Notes on the holdings of Rio Plata Silver Mines in Silver Basin, Keno Hill, Yukon Territory Property File Collection Miscellaneous Company Documents
ARMC014865 Surface plan map of Yukeno shaft area, Elsa, Y.T. Property File Collection Geoscience Map (General)
ARMC014850 Sketch plan of gold showing near Formo Shaft - Galena Hill, Yukon Territory - Figure 2a Property File Collection Geoscience Map (General)
ARMC014855 Rio Plata Silver Mines Ltd. - Analysis of the Formo workings Property File Collection Miscellaneous Company Documents
ARMC014857 Rio Plata Silver Mines Ltd. - Silver Basin claim - claim and company information Property File Collection News Release
ARMC014866 Map - Yukeno workings of A. Smith Property File Collection Geoscience Map (General)
ARMC014867 Geological sketch - Formo drift Property File Collection Geoscience Map (Geological - Bedrock)
ARMC014851 Composite plan showing adits and surface detail - Formo group of claims - Galena Hill, Yukon Territory - Figure 3 Property File Collection Geoscience Map (General)
ARMC014868 Composite - Formo group Property File Collection Geoscience Map (Geological - Bedrock)
ARMC014863 Contour sketch map - Formo group - Yukeno Mines Ltd. Property File Collection Geoscience Map (General)
ARMC014873 Assay certificates - Silver Titan Mines Ltd. - Yukeno - File no. 1188-20 Property File Collection Assays
ARMC014854 Assay plan - 2600 ft. level - Formo group Property File Collection Geoscience Map (General)
ARMC014852 Assay plan - 2700 ft. level - Formo group Property File Collection Geoscience Map (General)
ARMC014853 Assay plan - 2700 ft. level - Formo group Property File Collection Geoscience Map (General)
ARMC014861 Assay record sheets - Yukeno Mines Ltd. - Formo Group Property File Collection Assays
ARMC014864 Claim map - Rio Plata Silver Mines Ltd. N.P.L. Property File Collection Geoscience Map (General)

Resource/Reserve

Year Zone Type Commodity Grade Tonnage Amount Reported Amount 43-101 Compliant Cut-off
1986 FORMO (UNDERGROUND) Historical Estimate lead 6.9 % 40,000 No No Unknown
Listed as estimated reserves.
1986 FORMO (UNDERGROUND) Historical Estimate silver 550 g/t 40,000 No No Unknown
Listed as estimated reserves.
1986 FORMO (UNDERGROUND) Historical Estimate zinc 10.7 % 40,000 No No Unknown
Listed as estimated reserves.