The Khayyam mine has 8 adits with a total of about 548 m (1,800 feet) of underground workings, and numerous pits, trenches, and open cuts – some of these adits are accessible today. The Khayyam mine was serviced by aerial and surface trams, 1 mile and 2⅓ miles long respectively, to transport the ore from the mine and stockpiled in bunkers at the head of McKenzie Inlet located at tidewater approximately 2.4 km (1.5 mi) to the east-northeast of the Khayyam mine. An ore shipping terminal was developed and ore was then loaded into boats and shipments were made to the Tyee smelter at Ladysinith in British Columbia, Canada. The ore was composed principally of pyrite, with a small percentage of chalcopyrite and accompanied by pyrrhotite, sphalerite, and some magnetite.
The Khayyam and Stumble-On deposit surface and underground workings was extensively sampled by U.S. Bureau of Mines (USBM) in 1944 and 1945 (Fosse, 1946) and extensively investigated, sampled, mapped and released resource estimate in 1995 by USBM (Maas, K.M., Bittenbender, P E., and Still, J.C., 1995). Bureau geologists took 41 samples of massive sulfide lenses and country rock from surface trenches, outcrops, and the 8 adits at the Khayyam mine. A sample taken from a stope in the Powell adit assayed 2.61% copper and 1.54% zinc. Two samples taken in Adit 4 assayed 4.66% and 4.68% copper across widths of 0.9 and 1.5 m, respectively with silver values from averaging 37.4 g/t silver. A sample from Adit 5 assayed 3.38% copper and 1.0 g/t gold across 2.4 m. A sample from Adit 6 assayed 2.85% copper and 1,91 g/t gold across 1.5 m. All 27 measured samples taken from the Khayyam mine had an average of 0.832 g/t gold, 11.6 g/t silver, 1.27% copper, and 0.30% zinc.
Bureau personnel collected a 125 kg sample of massive sulfide from the Khayyam mine area (Maas, K.M., Bittenbender, P E., and Still, J.C., 1995) for metallurgical testing by the Bureau's Salt Lake City, Research Center. Initial assay of the bulk sample showed 1.3 g/t gold and 13.0 g/t silver, along with a calculated head for base metal flotation tests of 2.5% copper and 1.4% zinc. Preliminary tests showed a 99.25% recovery of copper and 91.0% recovery of zinc from a minus 150 mesh grind.
The Stumble-On prospect was originally located in 1901 situated approximately 1.5 km east of the Khayyam Mine. Developments on the property were accomplished before 1907 and include excavated open cuts on the strike of the ore body, several trenches, and two adits with about 120 m of workings. The host rocks and mineralization at the Stumble-On prospect are similar to those at the Khayyam Mine. A massive sulfide lens of pyrite with chalcopyrite, sphalerite, pyrrhotite, and magnetite is up to 2.5 m thick and extends for at least 170 m along strike. The sulfide lens is conformable with the host mafic and intermediate schists. A ground VLF electromagnetic survey, published by USBM (Barrie and Kyle, 1988), clearly indicates the Stumble-On massive sulfide lens and conductive body may extend at depth to the east of the present prospect workings and may even be thicker in that direction. Minor faults and mafic dikes, probably temporally related to the faults, crosscut the massive sulfide lens roughly perpendicular to strike.
USBM geologists mapped and sampled the surface and underground workings at the Stumble-On prospect. A total of 28 samples were taken from the Stumble-On upper and lower adits, outcrops, trenches, and ore stockpiles outside each adit. Selected samples upper adit assayed up to 5.96% copper, 3.61% zinc, 43.7 g/t silver, and 3.91 g/t gold. Two continuous chip samples across 0.9 and 1.5 m in the open cut above the upper adit assayed 3.17% and 8.93% copper, respectively. A sample taken from an outcrop immediately to the east of the mine, assayed 4.57% copper, 15.4 g/t silver, and 6.90 g/t gold across 1.5 m. The average of all 24 measured samples from the Stumble-On prospect reveal 1.12 g/t gold, 6.91 g/t silver, 0.92% copper, and 0.20% zinc.
Samples collected by USBM in 2001 at the Khayyam and Stumble-On mine sites assayed up to 136 g/t (4.36 oz/t) silver, 8.67 g/t gold, 53.80 g/t tellurium, 34.2% copper, 56.7% zinc, 398 ppm cobalt, 121 g/t gallium and 2,160 ppm cadmium.
Only minor exploration (post 1946) has been conducted on the Khayyam and Stumble-On mine sites and prospects conducted by the Banner Mining Company, Noranda Exploration Inc., Duval Corporation, Anaconda Copper, Cominco Exploration, Homestake Mining Company, and Kennecott.
Most recently, in 2007, The Niblack Mining Corp. staked the Khayyam mine and the Stumble-on prospect named their “Cayenne property” (Niblack Mining Corp., 2008). Niblack carried out geologic mapping, collected rock samples, and conducted a 2.5 line kilometer controlled source audio-magnetotellurics (CSAMT) geophysical survey. CSAMT is a high-resolution resistivity mapping tool effective at detecting conductive sulphide mineralization in the subsurface. Multiple strong conductors were identified at depth, some of which correlate well with known sulphide lenses near surface, while others may represent new sulphide lenses. Chip sampling across a two metre wide surface outcrop of massive sulphide yielded 9.66% zinc, 0.88% copper, 6.2 g/t silver and 0.30 g/t gold. Sampling of 0.3 to 0.5 metre boulders from the mine dump assayed up to 14.6% zinc, 15.4% copper, 109 g/t silver, and 5.72 g/t gold. The Stumble-On deposit is located 1.5km to the east and along strike from Khayyam. Potential for discovery below the existing mine workings and between the two deposits is high.
Historical Production
Between 1906 and 1909 the Khayyam mine produced 177,769 lb (80,635 kg) copper; 129 Oz (4.01 kg) gold; and 1,711 Oz (53.21 kg) silver. There are no production records available for the Stumble-On mine.
Resource Estimate
A resource estimate was defined at the Khayyam mine in 1944 and reported by USBM (Maas, K.M., Bittenbender, P E., and Still, J.C., 1995) which comprises of indicated and inferred resources totalling 85,000 tons of volcanogenic massive sulphide (VMS) ore that contains an average 2.94% copper, 0.79% zinc, 1.3 g/t gold, 17 g/t silver, and 39.7% sulfur. No calculation of the resources was made for the Stumble-On mine – the orebody remains in-situ today. It is to be noted that the mineral resource estimate is not compliant to JORC Code or National Instruments NI 43-101 standards for reporting mineral resources and reserves.