The Gold Field (Spud Valley) occurrence lies in the Zeballos gold camp and is located on a ridge separating Spud and Goldvalley Creeks. The (main) No. 7 adit portal is located at an elevation of 377 metres on the east side of the Spud Creek valley.

Regionally, the area is underlain by Upper Triassic to Lower Jurassic Bonanza Group basaltic to rhyolitic volcanic rocks. Conformably underlying the Bonanza volcanic rocks are limestones and limy clastics of the Triassic to Lower Jurassic Parson Bay Formation (Bonanza and Vancouver groups) and Upper Triassic Quatsino Formation (Vancouver Group), and tholeiitic basalts of the Upper Triassic Karmutsen Formation (Vancouver Group). Dioritic to granodioritic plutons of the Zeballos intrusion phase of the Jurassic Island Plutonic Suite have intruded all older rocks. The Zeballos stock, a quartz diorite phase of the Eocene to Oligocene Mount Washington Plutonic Suite, is spatially related to gold-quartz veining in the area. Bedded rocks are predominantly northwest striking, southwest dipping, and anticlinally folded about a northwest axis.

Recorded production for the Zeballos gold camp totals 9465 kilograms of gold and 4119 kilograms of silver from 652 000 tonnes of ore mined (Fieldwork 1982, page 291). Most of the production came from the Spud Valley deposits (MINFILE 092L 013 and 092L 211) and Privateer mine (MINFILE 092L 008).

The Gold Field mine and associated vein occurrences are hosted in quartz diorite of the Zeballos stock, near its western contact with Bonanza Group andesites and tuffs. Seven veins are recognized, among them the Goldfield and its branching Spur vein, which together produced all the ore in the past. The AT, Linton and Linton North veins are located over a length of 250 metres to the northwest from the Goldfield vein, and the GF2 and GF5 veins are located short distances southeast of the Goldfield vein. The Roper vein (MINFILE 092L 013) is located approximately 200 metres southeast of the Goldfield vein.

The veins are associated with steeply dipping, northeast-trending structures. Narrow zones of chloritic and argillic alteration envelope the structures, ranging from a few centimetres to a metre or more in width. Mafic components of the quartz diorite are altered to chlorite and feldspar minerals are clay altered. Only the Goldfield and Spur veins are detailed here. Other veins are indicated on various maps and reports and have undergone some exploration activity.

The Goldfield vein strikes 050 to 062 degrees, dips 75 to 85 degrees north, and ranges in width from less than 1 to 40 centimetres. It follows a generally well-defined shear zone up to 60 centimetres wide. The vein, locally sheeted, is generally competent with thin bands of fine-grained pyrite, arsenopyrite, sphalerite, galena and chalcopyrite in a quartz (±calcite) gangue. Weakly mineralized, short, diagonal, east striking veins are also present.

The Spur vein strikes 070 degrees, dips vertically to 85 degrees north, and branches off the Goldfield vein, with which it shows a strong similarity. It averages 15 centimetres in width, generally less than that of the mineralization at the Goldfield vein, but contains some high-grade sections. Assays up to 6.86 grams per tonne gold are reported (Bulletin 27, page 92). The northeast end of the Spur vein ends in 0.6 centimetre of quartz within 1.2 centimetres of gouge.

In 1983, bulk sampling yielded an average of 29.02 grams per tonne gold and 7.18 grams per tonne silver (Property File - McAdam Resources [1989-04-01]: News Clippings - Gold Field [Spud Valley]).

In 1986 and 1987, drilling on the Linton vein encountered mineralized intersections over a strike length of 540 metres, including intercepts of 3.81 grams per tonne gold over 1.2 metres in hole G-8, 22.01 grams per tonne gold over 0.18 metre in hole G-11, 24.76 grams per tonne gold over 0.31 metre in hole G-12 and 17.16 grams per tonne gold over 1.2 metres in hole G-13, whereas drilling on the AT vein yielded intercepts of 7.18 grams per tonne gold over 0.9 metre in hole G-3,83.64 grams per tonne gold over 1 metre in hole G-6, 8.92 grams per tonne gold over 1.34 metres in hole G-9, 5.18 grams per tonne gold over 1.0 metre in hole G-10, 223.5 grams per tonne gold over 0.64 metre in hole G-18, 109.3 grams per tonne gold over 0.24 metre in hole G-20 and 88.64 grams per tonne gold over 0.21 metre in hole G-24 (Property File - McAdam Resources [1989-04-01]: News Clippings - Gold Field [Spud Valley]; McAdam Resources Inc. [1988-04-01]: Prospectus Report on the Spud Valley Project).

Also at this time, drilling on the Linton North vein yielded 6.9 grams per tonne gold over 0.9 metre in hole G-2 and 31.55 grams per tonne gold over 0.27 metre in hole G-24 (Property File - McAdam Resources [1989-04-01]: News Clippings - Gold Field [Spud Valley]; McAdam Resources Inc. [1988-04-01]: Prospectus Report on the Spud Valley Project).

In 1988, drifting on the Linton North vein followed the vein for 61 metres yielding an average of 12.07 grams per tonne gold over a width of 1.2 metres and a length of 59.0 metres (Property File - McAdam Resources Inc. [1988-04-01]: Prospectus Report on the Spud Valley Project). Also at this time, drifting on the No. 7 level Spur vein yielded 7.64 grams per tonne gold over a width of 1.2 metres and a length of 14.7 metres along strike, whereas drilling on the A vein yielded up to 75.94 grams per tonne gold over 1.2 metres (Property File - McAdam Resources [1989-04-01]: News Clippings - Gold Field [Spud Valley]).

In 1989, panel sampling on the 7A sublevel yielded 26.0 grams per tonne gold over a width of 1.2 metres and a length of 14.1 metres (Property File - The Northern Miner [1989-11-13]: News Clipping - McAdam drifting at Spud Valley).

Production figures are combined production for the Roper (MINFILE 092L 013) and Gold Field occurrences. The combined occurrences are known as Spud Valley. Bulletin 27 (pages 92, 94) reports production from the Spur vein totalling 24 130 tonnes averaging 9.6 grams per tonne gold. The Goldfield vein produced 63 500 tonnes grading 11.7 grams per tonne gold.

Proven/probable/possible reserves in four veins (combined with the Roper deposit, MINFILE 092L 013) are 220 429 tonnes grading 10.7 grams per tonne gold. In view of an unsuccessful 1989 mill test, the reserve figure of 49 890 tonnes in old workings grading 4.6 grams per tonne gold reported in 1942 near the end of the mine life may be more credible (McAdam Resources Inc. [1988-04-01]: Prospectus Report on the Spud Valley Project).

Work History

The area has been explored since the 1930s. The original Goldfield claim was staked in 1935 and a 9.1 tonne per day mill was constructed. Minor production occurred in 1936. In 1937, Spud Valley Gold Mines Ltd. acquired the property. In 1938, a 113.4 tonne per day mill was constructed with production occurring during 1938 through 1942 from seven adits and associated levels and connected raises being developed from elevations of approximately 372 to 630 metres.

In 1983, Glencair Resources Inc. completed a program of bulk sampling on the Goldfield and Spur veins. During 1985 through 1989, McAdam Resources completed programs of diamond drilling, underground development and rehabilitation, and mill testing on the Spud Valley property. This work included 32 drillholes, totalling 9313.8 metres, 518 metres of drifting on the No. 7 level and development of the No. 8 level.

In 2003, Canalska Ventures Ltd. completed a regional program of rock, silt and soil sampling on the area. During 2011 through 2019, North Bay Resources Inc. completed programs of prospecting and geochemical (rock and silt) sampling the area as the Zeballos Gold property.