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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  20-May-13 by Nicole Barlow(NB)

Summary Help Help

NMI 092H10 Cr1
BCGS Map 092H056
Status Prospect NTS Map 092H10W
Latitude 49º 32' 21" N UTM 10 (NAD 83)
Longitude 120º 54' 02" W Northing 5489513
Easting 651889
Commodities Platinum, Chromium, Palladium, Gold Deposit Types M05 : Alaskan-type Pt+/-Os+/-Rh+/-Ir
Tectonic Belt Intermontane Terrane Quesnel, Plutonic Rocks
Capsule Geology

The platinum-chromite Grasshopper prospect outcrops along the southwest flank of Grasshopper Mountain, near its summit, 10 kilometres west-southwest of the town of Tulameen, and approximately 26 kilometres northwest of Princeton.

Grasshopper Mountain is underlain by dunite and peridotite of the Early Jurassic Tulameen Ultramafic Complex, a zoned Alaskan-type intrusive complex. The dunite-rich core of the complex extends south-southeast from Grasshopper Mountain for 5 kilometres to Olivine Mountain, and is successively fringed by zones of clinopyroxenite and gabbro.

Near the summit of the mountain, the dunite is fine to medium grained and homogeneous. The rock is comprised of olivine, fine magnetite, accessory chromite and generally less than 40 per cent serpentine. Stronger zones of serpentinization are erratically distributed and confined to narrow fracture zones and variously oriented fissures containing up to 80 per cent serpentine.

Chromite is the principal accessory mineral, and occurs as erratically distributed clots, disseminations, stringers and isolated pods up to 1.0 by 0.5 metre in size. The mineral comprises 1 to 25 per cent of the dunite by volume, but no concentrations of economic interest are observed (Assessment Report 15516).

Platinum-bearing chromite is found in a northwest-trending zone 800 metres long and up to 300 metres wide. Chip sampling yielded elevated platinum values in five larger outcrops (zones A, B, C, D and E) and numerous smaller isolated occurrences within this zone. Average chromium and platinum values for the five larger outcrops are as follows (Assessment Report 15516, page 19):

Zone Area Chromium Platinum
(metres) (per cent) (grams per tonne)
A 4 x 1 1.200 1.150
B 4 x 1 1.144 2.210
C 6 x 6 17.427 2.915
D 6 x 5 4.712 2.340
E 5 x 7 0.883 1.355

Zones C, D and E occur near the southern end of the region of platinum-bearing chromite, in an area of coarsely disseminated chromite 250 metres long and 150 metres wide. The highest platinum value came from an isolated, irregularly-shaped chromite segregation in the vicinity of zones C and D, which assayed 16.0 grams per tonne platinum, 0.080 grams per tonne palladium and 20 per cent chromium over 1 metre (Assessment Report 15516, page 23). Subsequent drilling yielded values of up to 35 per cent chromium and 2.5 grams per tonne platinum (Assessment Report 19825, page 4).

The Grasshopper claims were first staked in 1978. Various exploration programs between 1979 and 1982 resulted in the analysis of 163 rock samples for platinum-palladium. One sample returned 720 parts per billion platinum with greater than 2 per cent chromium (Assessment Report 10063). The claims lapsed, were restaked in 1984 and optioned to Monica Resources Limited. Monica Resources carried out geochemical, geological and geophysical surveys with a focus on gold mineralization to the east of the Tulameen Ultramafic Complex, and additional geophysical surveys to the east of the claims near the Rabbitt gold mine. Between 1959 and 1970, and again between 1984 and 1986, Imperial Metals carried out a variety of exploration programs on several areas immediately surrounding the Grasshopper claims.

In 1986, Newmont Exploration of Canada Limited optioned the Tulameen Ultramafic complex portion of the claims. Work by Newmont included geochemistry, prospecting, geological mapping and ground magnetics. Results from the program established a connection between chromium-rich rocks and platinum in the dunite. A broad northwest-trending zone of platinum-bearing chromitiferous dunite, approximately 300 metres by 800 metres in size, was identified. In 1987, the property was optioned to Longreach Resources Limited, and exploration efforts were focused on the chromium-enriched platinum-bearing zone identified by Newmont the previous year. The 1988 exploration program consisted of trenching and percussion drilling. In total, 1533 metres of percussion drilling were completed and each hole was sampled from top to bottom. In 1987 and 1989, the Grasshopper claims were included in Twin Eagle Resources Incorporated’s exploration of the Gold Mount property. Efforts were focused on gold exploration near the Rabbitt mine workings, but also included property-wide geophysical surveys.

Phoenix Gold Resources optioned the property and in 1997 completed nine diamond drillholes totalling 410 metres of BX core and 284 metres of NQ core. The program failed to return significant results; however, only 62 samples were taken and less than 5 per cent of the core was assayed. Work commitments on the property were not fulfilled and the option was dropped in 1999. It has been suggested that results from the Phoenix program were misguided as conclusions were based on very limited assays on selected samples from across the property (Assessment Report 27114). In 2001, Bright Star Ventures Limited relogged and sampled the 1997 core drilled by Phoenix. Analysis indicated elevated platinum levels over large intervals and showed that coarse-grained platinum was present in dunite and not necessarily restricted to chromitiferous dunite.

Drilling by Newmont Exploration of Canada Ltd. encountered up to 9.26 grams per tonne platinum over 3.05 metres (Exploration in BC 1997, page 40). Results from the 1988 percussion drilling program included 5.2 metres averaging 4,715 parts per billion platinum and 15.2 metres averaging 622 parts per billion platinum (Assessment Report 27114). The 2001 assays of the 1997 diamond drillcore returned several significant results, including up to 0.29 grams per tonne platinum over 48.78 metres and several 3.05 metre long intervals of 30.89, 1.64, 1.41, and 1.45 grams per tonne platinum (Assessment Report 27114).

EM GEOFILE 2000-2, 2000-5
EMPR AR 1917-27
EMPR ASS RPT 128, 7944, *10063, *15516, *19825, 27009, *27114
EMPR EXPL 1988-B71-B81; 1997-40
EMPR FIELDWORK 1981, pp. 218-222; 1987, pp. 281-294
EMPR OF 1986-7, pp. 6-11; 1988-25; 1990-27, pp. 33,34
EMPR P 1992-6
EMPR PF (Monica Resources Ltd. (1987): Statement of Material Facts
No. 108/87, Vancouver Stock Exchange; Twin Eagle Resources Inc.
(1987): Statement of Material Facts No. 117/87, Vancouver Stock
Exchange; Scorpion Resources Inc. (1988): Prospectus, Vancouver
Stock Exchange, page 10 (see 092HNE014))
EMR MP Metal Controller File 167-C 1-2-45
GSC EC GEOL No. 13, pp. 89-94 (1934)
GSC MAP 46A; 888A; 889A; 1386A; 41-1989
GSC MEM 26, pp. 51,153-155,168-170; 243, pp. 33,34,60,109,110
GSC P 85-1A, pp. 349-358
GSC SUM RPT 1923, pp. 84A-101A
CJES Vol. 6, pp. 399-425 (1969); Vol. 24, pp. 2521-2536 (1987)
GCNL #205(Oct. 24), 1986; #45(Mar. 5),Mar. 23, 1987; #133, 1988;
#155(Aug.13), #181(Sept.19), #227(Nov.26), 1997
PR REL Bright Star Ventures Ltd., Jul. 19, 2002
Findlay, D.C. (1963): Petrology of the Tulameen Ultramafic Complex,
Yale District, British Columbia, unpublished Ph.D. thesis, Queen's
University, 415 pages