The UNION mine is located on the east side of Mount Franklin, approximately 1.2 kilometres east-southeast of the summit. Mine buildings are located in the valley bottom on the PAPER DOLLAR Crown grant Lot 1677s, which is on the west side of a western tributary of Glouster Creek.

The UNION mine has been developed in greenstone, tuff, argillite, siltstone and conglomerate of the Devonian-Triassic Harper Ranch Group. Several hundred metres to the west there is a cover of andesite and dacite flows and tuffs of the Eocene Marron Formation, Penticton Group. Syenite of the Eocene Coryell Intrusions is found about 500 metres to the north.

The underground workings are on 4 levels over a vertical range of about 129 metres. A glory hole is located about 200 metres above the valley floor. The mine development followed a large, segmented quartz vein which is collectively known as the Union vein. Underground individual fault segments have also been named. Subsidiary quartz veins may also exist. The vein is mineralized with pyrite, sphalerite, galena, argentite and chalcopyrite. Pyrargyrite has also been noted. The vein strikes approximately 080 degrees and dips vertically. The mine area is structurally complex and is dominated by steeply angled faults, the most significant of which are the Union and the Number 1 faults. The Union fault strikes northwesterly and dips 80 to 85 degrees to the southwest. It appears to cut off the ore-bearing vein at all levels in the mine. On the No. 1 and No. 4 levels the vein appears to change direction and follow the Union fault, suggesting that the fault may be contemporaneous with the vein. The fault persists beyond the end of the vein. Brecciated, sheared and silicified country rock along the vein indicates movement during formation.

The UNION claim was located by L. Johnson and associates in 1906 and Crown granted as Lot 1022s in 1914. Adjacent Crown grants include the PAPER DOLLAR (L. 1677s) and the IDAHO (L. 1679s). Initial assessment work focused on a vein containing galena with silver value; however, in 1913, a siliceous zone with high gold and silver values was discovered. This zone, measuring about 2.4 metres in width, contains a small amount of pyrite, limonite and garnet and is believed to be a siliceous replacement of a limestone. Five cars of ore were shipped to the smelter in Grand Forks that year (Minister of Mines Annual Report 1913, page 168). A 2.4-metre wide sample taken from the opencut assayed 34.2 grams per tonne gold and 2018 grams per tonne silver (Minister of Mines Annual Report 1913, page 168).

Initial ore production was from a large open cut, but 2 adits, located 25 and 150 metres below the open cut, were started in 1913. The upper adit exposed both the galena-rich vein and the siliceous replacement zone, which at this point had narrowed to 90 centimetres in width. A sample assayed 80 grams per tonne gold and 441 grams per tonne silver (Minister of Mines Annual Report 1913, page 168). The lower adit also encountered the siliceous zone but precious metal assays were much lower. Recorded production during the period 1913-20 was 3206 tonnes which yielded 77850 grams of gold and 3.62 million grams of silver. Underground development during this period was on 3 levels.

In 1918, the platinum potential of the UNION mine was investigated. Three samples collected from oxidized material from vein outcrops and ore pulps assayed a trace of platinum (Thomlinson, 1920).

In 1927, the UNION mine and surrounding Crown grants were bonded to J.F. McCarthy of the Hecla Mining Company, based in Wallace, Idaho. Development in 1928 consisted of 975 metres of drifting and crosscuts, and the No. 4 adit was begun 60 metres below level No. 3. In 1929, raises were driven between levels 2,3 and 4, and a 145-tonne per day mill constructed. Production commenced in 1930, with 33,462 tonnes mined and milled to produce 1001 tonnes of concentrate (Minister of Mines Annual Report 1930, page 226). The total length of underground workings, at the end of 1930, was 990 metres over a vertical range of 129 metres, not including the glory hole above level No. 1. Most of the ore was mined from between levels No. 1 and 2; very little ore was found on level No. 4. The width of the ore zone varied from 1.5 to 7.6 metres and its boundaries could only be identified through assays. Diamond drilling in 1931 identified a new, although small, ore body north of the level No. 1 tunnel. The new ore body contained free-milling gold necessitating the installation of 2 Wilfley tables to the mill circuit. In 1931, 51,465 tonnes were mined, of which 59 tonnes was of such high-grade that it was shipped directly to smelters at Trail and Bradley, Idaho (Minister of Mines Annual Report 1931, page 118).

In 1932, 24,020 tonnes were mined, of which 24,000 tonnes were milled, producing 4.7 million grams of silver and 597,737 grams of gold. The mill closed in October, 1932 because of insufficient ore.

In 1933, the mine closed because of a lack of ore, despite extensive underground exploration and development work that year. A total of 2861 tonnes of ore was mined and 3342 tonnes milled in 1933 (Minister of Mines Annual Report 1933, page 148). Some of the tonnage milled may have been supplied from the adjacent HOMESTAKE (082ENE051) property, which was owned by the same J.F. McCarthy interests. The HOMESTAKE had been the focus of an extensive underground program of drifting and cross cutting in 1933, and the ore was noted to be similar to that of the UNION. However, if production took place on the HOMESTAKE in 1933, it was not recorded.

In late 1933, a cyanide plant was constructed to treat an estimated reserve of approximately 90,000 tonnes of tailings grading 1.7 grams per tonne gold, and 68.4 grams per tonne silver (Minister of Mines Annual Report 1933, page 148). During the period 1934-36, Hecla mined and milled unstoped ore-remnants from the mine, and treated old mill tailings. A total of 48,129 tonnes of ore and tailings were treated during this period, of which the tailings represent a substantial portion of the total. Approximately 2.28 million grams of silver, 68,085 grams of gold, 5419 kilograms of lead and 14,326 kilograms of zinc were produced.

In 1937, the UNION mine was leased by W.E. McArthur from J.F. McCarthy. Over the next 6 years, 838 metres of diamond drilling, surface stripping and some limited underground development work was carried out, with most of this work being performed during 1940-42. Production during the period 1937-42 was 7536 tonnes of ore which yielded 2.84 million grams of silver, 64,787 grams of gold, 1140 kilograms of lead and 1483 kilograms of zinc.

In 1947, C.E. and J.E. Small shipped 5 tonnes of ore from the UNION mine to the Trail smelter. This produced 31 grams of gold and 1337 grams of silver (Minister of Mines Annual Report 1947, page 157).

In 1971, Mustang Resources Ltd., who had optioned the UNION property from Hecla, erected a batch process cyanide plant and began a leaching process using a closed-circuit method. Gold and silver were recovered in a precipitator using zinc dust, but the operation proved uneconomic and closed after operating for several months. No production was recorded.

In 1979, Pearl Resources Ltd. acquired much of the area around the UNION mine, and in 1980, optioned the UNION property from Hecla Mining Company. In late 1980, Pearl Resources carried out a 5-hole, 675-metre diamond drill program to test the westerly trend of the UNION structure. The program was not able to trace the structure and assays results were poor.

In 1984, Pearl Resources embarked on a major program of diamond drilling following the rehabilitation of the No. 4 level and its northwest extension. A total of 34 percussion drillholes (397 metres) and 19 diamond drillholes (1076 metres) were drilled underground. The results of the drill program were mixed. The extension of the Gold Stope Vein was encountered but assay results were poor. One hole drilled below the Schulz Vein failed to intersect its extension. The Main Vein below level No. 3 was barren of gold, except at the western end of the vein structure, where drillhole DDH PU-8 intersected 1.65 metres grading 37.25 grams per tonne gold and 2150 grams per tonne silver (Assessment Report 13710).

Four areas with potential reserves were identified by Pearl Resources in 1984. The Main Union Vein, between the No. 3 and No. 4 levels contains a possible reserve of about 7000 tonnes grading 32.5 grams per tonne gold and 1858 grams per tonne silver over a width of 1.5 metres (Assessment Report 13710). The Union South Zone, between the No. 2 level and the surface, contains a possible reserve of about 7000 tonnes grading 8.7 grams per tonne gold and 294 grams per tonne silver over 1.5 metres width (Assessment Report 13710). Surface ore dumps contained a possible reserve of about 16,000 tonnes of ore grading 2.2 grams per tonne gold and 65 grams per tonne silver (Assessment Report 13710). Preliminary leach-tests on minus 1.58 centimetre high-grade dump material suggest poor recovery; only 10 per cent of the gold and 29 per cent of the silver was recovered in a 35 day column leaching test of material with an initial head grade of 8.28 grams per tonne gold and 118 grams per tonne silver (Assessment Report 13710). Tailings from earlier production contained a possible reserve of 70,000 tonnes grading 1.5 grams per tonne gold and 48.9 grams per tonne silver (Assessment Report 13710). Cold bottle roll tests of the tailings yielded 65 per cent gold and 48 per cent silver recovery; a 35-day column leach test indicated recoveries of 74 per cent gold and 71 per cent silver (Assessment Report 13710).

In 1985, 24K Mining Inc. optioned the UNION property from Pearl Resources Ltd.; and in 1986, 24K Mining merged with Summit Ventures Inc. to form Sumac Ventures Inc. Work in 1986, and continuing into 1987, consisted of diamond drilling, rehabilitation of the No. 3 and No. 4 levels, and sub-level drifting and raising preparatory to developing the Main Union Vein reserve. Assays confirmed previous results (Northern Miner, April 7, 1986; Northern Miner, February 23, 1987); however, no underground production is recorded.

In October 1987, Sumac Ventures began heap leaching material from the dumps and tailings. A total of 5000 grams of gold and 150,000 grams of silver were produced from 13,600 tonnes of tailings and dump material (Exploration in British Columbia 1987, page A63). Small amounts of platinum and palladium were recovered in testing (Exploration in British Columbia 1987, page A63).

Sumac Venture's heap leach continued in 1988 with production of 8000 grams of gold and 243,000 grams of silver being produced from 10,900 tonnes of ore (Exploration in British Columbia 1988, page A5). It was estimated in 1988 that about 70,000 tonnes of tailings and old dump material were available for treatment (Exploration in British Columbia 1988, page A5). No grades were given in the estimate.

In 1989, 18,000 tonnes of ore were heap leached which produced 300 grams of gold (Mineral Statistics 1990, page 29).

No further significant work was done in the Franklin Camp until 2001, when Tuxedo Resources Ltd. assembled a very large land package, by way of 7 separate option agreements. Tuxedo’s Franklin property included the majority of the current Union property. Tuxedo flew an airborne geophysical survey over essentially the entire Franklin Camp during 2001. By the end of the 2003 work program, Tuxedo Resources had earned 100% ownership in some of the claims in the camp. Early in 2004 Tuxedo Resources (now Signature Resources) terminated the option agreements on all its remaining claims in the camp.

In 2004, Solitaire Minerals Corp. optioned the Union property and completed a work program consisting of rock sampling, excavator trenching (350 lineal meters in 11 trenches) and diamond drilling (1643 meters in 7 holes). Rock sampling and trenching at the Cabin Zone and drilling the Gloucester EM conductor failed to uncover any significant mineralization. Trenching at the White Bear epithermal zone returned elevated gold values, to 330 ppb Au. A single drill hole was drilled to test for an increase in grade with depth but no elevated precious metals were yielded. Five trenches and 1 drill hole tested the western portion of the Maple Leaf Crush Zone, a major east-west trending structure with associated mineralization. Elevated gold was found in trench samples but the drill hole yielded poor results. Four diamond drill holes were drilled at the West Union target, in an attempt to locate the western faulted offset of the Union Vein, west of the Maple Leaf fault and beneath post-mineral sedimentary cover. Only slightly elevated precious metal values were found.