Idaho

By Gillerman, V S; Bennett, E H; Weaver, M J

With commodity prices still “red hot,” Idaho’s preliminary value for nonfuel mineral production in 2006 was estimated by the U.S. Geological Survey (USGS) to be $810 million. This was slightly down from the final 2005 total of $906 million for Idaho’s nonfuel mineral production value. The 2005 value was a record for Idaho.

Molybdenum from the Thompson Creek Mine makes up more than half the value because of the mine’s sizable production and the metal’s sustained high price. Molybdenum oxide sold in the mid- $20s/lb range in 2006 and $25 to 40/lb range in 2005. Precious and base metals from northern Idaho were also significant contributors, as metals accounted for 63 percent of the state’s mineral value in 2006 (Fig. 1). New Jersey Mining’s Golden Chest Mine contributed a full year of gold production. The price of silver, Idaho’s signature metal, was sterling as it traded from 32 to 41 cents/g ($8 to $14/o/ ) during the year. In addition, the preliminary 2006 statistics show significant jumps in both quantity and value of crushed stone, construction sand and gravel, and cement. This reflects the vibrant residential and commercial construction ongoing in many parts of Idaho during the year.

Principal minerals by value in 2006 were molybdenum concentrates, construction sand and gravel, phosphate rock, silver and crushed stone. Idaho ranked second in industrial garnet and zeolite production, third in phosphate rock and silver, fourth in molybdenum and pumice production, and 26th overall among the states, according to the USGS. Mining employment peaked at 2,416 people in the second quarter of 2006 and was down to 2,318 by the end of the year. Overall, this was about 10 percent higher than 2005, reflecting workers needed for new operations and development work. The phosphate processing plants also employ more than 1,000 chemical workers in southeastern Idaho.

Metal mining

It was a busy year for miners and investors in the Coeur d’Alene District in Shoshone County in north Idaho. More than 37 Mt (1.193 billion oz) of silver have been produced from the extensive and high grade quarlz-siderite-sulfide veins, which contain significant lead or copper in addition to silver. Two large underground mines, the Lucky Friday and the Galena, were in operation. A third, the Sunshine Mine, had underground development under way. In addition, a new gold mine called the Golden Chest Mine, operated at Murray, just north of the main district.

Miners were reported to be in short supply and exploration was lively.

Hecla’s Lucky Friday unit was a shining light with a 19-percent increase in silver production to more than 89.3 t (2.87 million oz) of silver at a total cash cost of 11 cents/g ($3.65/oz) from the Gold Hunter expansion area. Multiple veins were mined from both the 4900 and the new 5900 access levels (Fig. 2). Byproduct metal values contributed to lowering the cash costs. Just as critically, the silver resource increased by 34 percent (to 364 kt or 117 million oz) due to development and exploration drilling. The 5900 level access drift was completed as well as mill improvements such as a third-stage crushing circuit and additional flotation capacity. Hecla also acquired land for a new tailings facility in anticipation of the lengthened mine life. Exploration drilling from the 5900 level intersected mineralized veins down near the 7900 level and generated better understanding of the multivein Gold Hunter system. Mining uses both mechanized and conventional slusher slopes to keep costs down and take advantage of the narrower, high grade tetrahedrite-rich veins. The mine had more than 170 employees in the summer.

On June 1, 2006, U.S. Silver acquired Coeur Silver Valley, including the operating Galena mine and mill, and the Coeur and Caladay mines. Production for 2006 from the Galena was more than 40 t (1.3 million oz) of silver with byproduct copper. U.S. Silver increased exploration and development at the Galena, implemented a new and more focused and efficient mining plan, and started needed infrastructure maintenance. The company has more than 150 employees and has been training miners. Exploration, including 18 km (59,630 ft) of diamond drilling by U.S. Silver, discovered a new high grade zone on the 2400 level with separate zones of silver/copper and silver/lead veins. High grade intercepts (more than 1.371 g/t or 40 oz/st silver and a lead /one) on the 3400 level are also heing evaluated. The company was making needed repairs to use the nearby Coeur mill in 2007. allowing for two separate metallurgical circuits to treat the different ores on the property. Production in 2007 is expected to increase substantially.

Sterling Mining was pursuing an aggressive development program at the Sunshine Mine near Kellogg. The first blast for the new Sterling Tunnel was on Jan. 31, 2006 and by year end. the 3.(vm (12-ft) wide tunnel was in more than half of the 1,737 m (5.701) ft) needed to connect with the Polaris Drift-Silver Summit Tunnel. The underground access will be used to drill “Upper Country” target areas of the Sunshine and Yankee Boy veins and up-djp projections of the Silver Syndicate and other veins. This included areas identified from surface geophysics as well as compilation of the old maps. Drill stations were cut as the tunnel advanced. Sterling is refurbishing the Sunshine Mill and Jewell shaft and stations, including the power and pumping capacity at the Jewell and Silver Summit escapeway. Employment was up to 30 people by year’s end. In October. Sterling purchased (for $4.5 million in cash and land) the Sunshine tailings facility from EMC, a subsidiary of Formation Capital. Sterling acquired it along with the Big Creek refinery and hydromelallurgical plant for its cobalt project in Lemhi County. Essential Metals continued to operate the Big Creek plant as a custom precious metal refinery.

New Jersey Mining, based in Kellogg, operated the Golden Chest Mine at Murray. It was the first full year of production for the small (450 t/m or 496 stpm), underground gold mine. High-grade ore was mined from the Katie-Dora vein, and the company drilled nine diamond holes on the nearby, deeper Idaho vein. New Jersey has a probable 9.3 t (300,000) probable oz) of gold blocked out, Ore is hauled to the New Jersey mill at Kellogg on a truck-loadable garbage dumpster.

New Jersey also began construction at the newly permitted (late 2005) Silver Strand Mine. Work included driving a new adit, road work and construction of office and dry buildings and water management facilities. Ore reserves (proven, probable and possible) stand at 17.5 kt (19.290 st) with 5.S7 g/t (0.17 oz/st) gold and 337 g/t (9.83 oz/st) silver. Ore will he shipped to the mill at Kellogg, where the company was constructing a concentrate leach tank circuit to enable onsite dore production. Cyanide neutralization and paste tailings disposal or backfill will be used to minimize water use and environmental impacts. Startup of the mill was expected in early 2007. along with production and development work at the Silver Strand.

Thompson Creek Mining had an excellent year at its large, openpit molybdenum mine near Challis in Custer County. Production is in the range of 4.9 kt (11 million lbs) a year of molybdenum, and the pit mining and stripping was in Phases 5 and 6. The privately held Thompson Creek Mining was purchased in October by Blue Pearl Mining, a Canadian junior. Purchase price for Thompson Creek was $575 million plus additional payments of up to $125 million contingent on molybdenum prices, and monies due vendors as of closing date. The sale included all of the company assets, including the mine and mill in Custer County, the 75 percent interest in the Endako Mine and plant in British Columbia, and the metallurgical refinery in Langeloth, PA. Molybdenum is a key component in high-end steel alloys and pipelines, valued for its corrosion-resistant properties. Blue Pearl has an interest in the Davidson deposit, an underground molybdenum deposit in British Columbia.

There are still a few small gold mines around the state. One is the Bond Mine at Pierce. Known originally as the Crescent, it was the first recorded lode mine in the state. Gold Pan Dan currently extracts gold from the No. 3 tunnel.

Meridian Gold’s Beartrack Mine in Lemhi County won the U.S. Bureau of Land Management’s (BLM) National 2006 Hard Rock Mine Reclamation award. The gold mine west of Salmon, ID, opened in 1994 and completed mining in March of 2000. Production was approximately 21.7 t (700.000 oz) of gold from the openpit, heap leach operation. Throughout its lifespan, the mine received strong support from the local community and maintained the highest standards for environmental performance. Pre-mine planning predictions for the 262 hm^sup 2^ (648-acre) site, estimated in the original permits, were close to the final project impacts. The mine offices are still on site, hut most reclamation work is complete.

Phosphate industry

Caribou County in southeastern Idaho hosts three openpit phosphate mines that annually extract more than 3.6 Mt (4 million st) of ore from the Permian Phosphoria Formation. The resource is in apatite-rich beds of the organic-rich shale of the Meade Peak Member. The pho\sphate rock is processed into either phosphoric acid fertilizers or elemental phosphorus. The industry is the economic mainstay of southeastern Idaho. All the companies were cooperating with agencies to study and remediate selenium releases from historic mine waste dumps.

Monsanto mined Phase 2 of the South Rasmussen Ridge Mine and did concurrent reclamation and backfilling (Fig. 3). The mine bought a new Hitachi shovel. Increased fuel costs have heavily impacted the operation, as the ore travels in company-owned triple trailers on the private haul road to the company’s elemental plant at Soda Springs. All of the plant’s output is used to manufacture Round-up herbicide. The mine and plant employ 450 Monsanto employees plus another 250 contractors. Monsanto also drilled and continued permitting work for its proposed Blackfool Bridge Mine, which has complicated ueologv and eround water issues.

J.R. Simplot operates the Smoky Canyon Mine near the Wyoming border. It is the largest operation and produced more than 1.8 Mt (2 million st) of ore in 2005. Mining was under way in the B and C pits, with the A, D and E portions being reclaimed. Ore is sent through a 140-km (87-mile) long slurry pipeline to the Don plant in Pocatello. where it is transformed into a variety of fertilizer products. The plant had record production in 2005 and 2006 was nearly as good. The draft environmental impact statement to expand into the F and G panels, also known as the Manning and Deer Creek leases, was released at the end of 2005 and comments were due in 2006. The additional reserves in F and G are critical to the mine, but the area lies within the Sage Creek Roadless Area and the best access is across private lands. A controversy arose in the summer when the company said it would consider using eminent domain under an obscure state law to put an access road across a ranch. The company offered $2.1 million to buy the 189-hm^sup 2^ (467-acre) ranch, but the offer was turned down.

As with other phosphate areas, a major issue in the DEIS was management of water and selenium. Both current and proposed mine plans require backfilling and capping of seleniferous overburden to prevent environmental releases.

Agrium operated the Dry Valley Mine, a former FMC property, after purchasing Asians’ assets there in 2005 and niothballing the Rasmussen Ridge Mine. Agrium acquired the C and D pit and was mining from the C pit primarily. Washington Group is the contract miner and employs about 100 people. Production is approximately 1.8 Mt/a (2 million stpy). Ore is sent by rail during the shipping season to Agrium’s phosphoric acid fertilizer plant at Conda. which employs another 260 people. The company was also doing delineation drilling on the D pit resource and constructing two large dewatering pits with synthetic liners.

Other industrial minerals

Idaho has a variety of small industrial mineral operations, mostly located in southern Idaho. The Gem State produces jasper, opal and star garnets. An environmental impact statement for the Idaho Panhandle Forest’s recreational garnet dig collected nearly as many public comments and controversies as a large mine would. The popular site revamped procedures to net visitors use sluice boxes on pre-mined gravel piles instead of doing their own digging. The garnet deposits are alluvial in nature and are found in riparian areas near St. Maries.

Idaho is second nationally in industrial garnet production. Emerald Creek Garnet, a subsidiary of WGI Heavy Minerals, mined and processed industrial grade garnets from the Emerald and Carpenter Creek basins and newly permitted reserves near the St. Maries River in Benewah County. Market prices were improved but sales volume was down slightly. The company was in a rebuilding phase, both domestically and overseas in India.

Sand and gravel and crushed stone production were up and other construction commodities had good years. Ash Grove Cement operated above plant capacity again at its facility in Inkom in southeastern Idaho. The company shipped more than 272 kt (3(10.000 st) of cement and imported clinker from another plant.

Dimension stone production included the Oakley stone quarries on Middle Mountain south of Oakley in Cassia County. Northern Stone Supply has the largest operation: Oakley Valley Stone, American Stone and Scnvanich Natural Stone also quarry the attractive tan to silver-colored micaceous quarlzite. At Boise. Table Rock Sandstone and Gerhard Borhonus Landscaping quarried silicified sandstone for use as high end landscaping and building stone. Idaho Travertine operated a stone cutting facility in Idaho Falls. L and W Stone continued to expand its Three Rivers stone quarry west of Challis. L and W worked on an environmental impact statement required for the expansion. Approximately 27.2 kt (30,000 st ) of the multi-colored argillaceous sandstone is quarried each season.

Hess Pumice produced 163 kt (180,000 st) of pumice in 2005 and at least that much in 2006 from its expanded Wrights Creek Mine north of Malad. Much of the pumice goes to the new Owens Corning plant, which manufactures cultured stone for housing construction. Hess Pumice has grown to more than 1 H) employees, and the company has become the leading supplier of finely ground, processed pumice in the United States. Canada, Brazil. Germany, United Kingdom, Japan and most of Southeast Asia. Ironically, a rival Italian pumice quarry has now been declared a World Heritage site and is shut down, thus providing Hess with an easier entry into European markets. Idaho Minerals, also owned by Hess, mined and expanded perlile, used principally in potting soil. U.S. Grout and a new company. BK Pumice, which makes cosmetics, are also owned by Hess and operate from Malad.

Bear River Zeolite, operated by U.S. Antimony, had 15 employees working round-the-clock at the zeolite mine and crushing and bagging plant near Preston in southeastern Idaho. Sales and prices were good and markets include water filtration and remediation, odor control, wastewater treatment and other uses for the high quality, high cation exchange capacity clinoptilolite. Last year’s expansion brought plant capacity to 136 kt (150.000 stpy).

Energy

US. Geothermal commissioned Ormat Nevada to construct Idaho’s first geothermal power plant at the Raft River project in Cassia County. The first plant will he a 10-MW binary facility, hut additional phases are already being planned at the property south of Malta. A $34-million financing was obtained in August. In the 1970s, the Department of Energy constructed a 5-MW demonstration project at Raft River.

Idaho held two oil and gas lease auctions during the year for a total of 125 parcels of state land. The BLM also had a lease sale. The main target areas are in the Overthrust Belt of the southeastern Idaho and the far western end of the Snake River Plain.

Exploration

2006 saw an increase in exploration around all parts of Idaho. Rising metal prices, especially gold and silver, were a clear reason. Many projects drilled previous discoveries, but some grassroots exploration was noted as well.

In the industrial minerals sector, i-minerals continued work at its Helmer-Bovill feldspar-quartzkaolin project in Latah County in northern Idaho. The company drilled four large diameter holes at its Kelly’s Basin feldspar/quartz deposit, hosted in granodiorite. The program was designed to test the block model based on a 61-m (2(H)- ft) drill grid and developed by SRK Consulting as part of an ongoing feasibility study. The company also obtained material for additional metallurgical testing by Minerals Research Laboratory in North Carolina.

New Jersey Mining had an aggressive exploration program in the greater Coeur d’Alene district. This included development work planned at the Coleman vein, claim staking at the newly discovered Gold Butte and CA prospects (an old Cominco Sullivan-type geophysical target) near Murray and acquisition of the Niagara copper-silver deposit near Murray in December. Niagara was explored by Earth Resources in the 1970s and an updated resource calculation, based on surface sampling and eight diamond drillholes, suggests a resource of 14.2 Mt (15.6 million st) with 20 g/t (0.58 oz/st) silver and 0.46 percent copper, hosted in the Revett Quart/ite. Additional exploration and drilling is expected in 2007 on several of New Jersey’s properties.

Also in north Idaho. Valencia Ventures completed a preliminary assessment of the Buffalo Gulch deposit within the Idaho Gold project near Elk City. Previous exploration included 150 RC holes drilled by Bema Gold from 1985 to 1988 and nine HO diamond drill holes by Idaho Consolidated Metals in 1996. The openpit. oxide indicated resource is 4.5 Mt (4.9 million st) at 0.8 g/t (0.02 oz/ t) gold (3.8 t or 115.750 oz) at Buffalo Gulch.

Golder Associates completed a recent NI 43-101 assessment calculating a $7.5-million net present value for the project. Beartooth Platinum retains a 49-percent interest in the properly, which also includes mineralized zones at three other gold prospects on the Orogrande Shear Zone – the Friday/Petsile, Deadwood and Dixie zones with potential resources in excess of 21.7 t (700,000 oz). Late in the year, Valencia and Beartooth announced an agreement to sell 100 percent of their interest to Clearwater Mining, a private company. Purchase price included a C$ 1.5-million payment to the sellers, with the hulk of it due on receipt of mine permits.

Kimberly Gold Mines held the Rescue Mine at Warren and small mines in the Marshall Mountains. The company rehabilitated the Rescue mill in 2004. Sidney Resources also worked property in the Warren district.

Journey Resources and Trio Gold announced results from 2006 exploration at the Empire Mine project near Mackay in the Alder Creek Mining District of Custer County. Journey is currently earning a 50-percent lease interest in the project. The claims cove\r a polymetallic skarn that hosts copper, zinc, gold and silver mineralization. To date. 33 holes, including live core holes, have been drilled in the AP pit area. Some 2006 intercepts include 9 m (29 ft) grading 0.26 percent copper and 5.7 g/t (0.16 oz/st) gold in JRC27. and 76 m (250 ft) of 0.44 percent copper in JRC26. Results will be used to complete a feasibility study on potential for a solvent extraction/ electrowinning (SX/EW) copper-zinc operation. A 1997 report by Cambior Exploration USA estimated the minable portion of the deposit at 30 Mt (33 million st) grading 0.44 percent copper, 0.2 percent zinc. 0.25 g/t (0.007 oz/st) gold, and 6.6 g/t (0.19 oz/ st) silver, at a 1:1 strip ratio. More work is planned in 2007.

Journey also drilled the Musgrove Creek gold project, located 40 km (25 miles) southwest of Salmon. The Musgrove area had several operating gold mines between 1908 and the mid-1930s. The deposit is an epithermal system hosted in Preeambrian Apple Creek Formation. It is a short distance southwest of the Beartrack Mine along the Trans- Challis Fault system. Journey is earning a 100-percent lease interest in the 86 unpatented claims. In May. Journey completed an updated technical report that examined existing geologic information and the 2004 NI 43-101 compliant mineral resource calculation (8 Mt or 8.8 million st at 1.22 g/t or 0.03 oz/st Au for 9.7 t or 10.8 st gold). Based on the recommendations from the report, geologic mapping and sampling and approximately 3,048 m (10,000 ft) of RC drilling were completed. To dale, 41 holes, totaling 11,248 m (36.902 ft) have been drilled. Significant intercepts from 2006 include numerous intervals of anomalous gold in the 0.69 to 1.4 g/t (0.02 to 0.04 oz/st) range with assays up to 7.2 g/t (0.21 oz/st) gold. Additional work is planned in 2007.

Salmon River Resources, a Vancouver junior, drilled the CAS property on Iron Creek. Sulfide mineralization, including cobalt and arsenopyrite with high gold was discovered on logging roads in the 1970s. The privately held property was drilled by Nevada Contact in 2002. Salmon River drilled five diamond drillholes, totaling 640 m (2.100 ft), into the Apple Creek Formation (Fig. 4).

Formation Capital with offices in Salmon, has conducted mineral exploration in the Idaho Cobalt Belt since 1993 and discovered a new deposit in the Blackbird District several years ago. Formation is proposing to develop the Idaho Cobalt Project (ICP). It will consist of an underground cobalt-copper-gold mine, mill and ancillary facilities on 145 unpatented claims. A draft environmental impact statement was prepared under the jurisdiction of the Salmon-Chains National Forest during 2006 and was released to the public early in 2007. The ICP will consist of a 726-t/d (800-st/pd) mine and mill complex to mine cobalt-copper-gold reserves at a production rate of 254 kt/a (280.000 stpy) of ore at full production. There are sufficient reserves and resources for 10 to 12 years of operation. Estimated annual production is 1.2 kt (2.6 million lbs) of cobalt. 907 t (2 million lbs) of copper, and 105 kg (3,400 oz) of gold averaged over the mine life. Underground mining methods will be used to extract ore from two deposits, the Ram and the Sunshine. Ore will be conveyed to a nearby mill situated on a high plateau locally referred to as the Big Flat. Concentrate from the mill will be trucked to an offsite processing facility and sent to their hydrometallurgical facility in Kellogg. Water quality concerns, because of past mining activities in the district, have been a major focus of the NEPA process. The company and the agencies have been working closely for several years to develop a mining operation plan that will have a minimal effect on the surrounding area. The operation will disturb less than 51 hm^sup 2^ (125 acres), will largely be an underground mining operation with all openings above the water table and will use no dangerous chemicals. Tailings will be dry stacked or backfilled underground and waste rock will be lined and covered. Advanced water treatment techniques will be employed to meet clean water standards and a post mining contingency plan including pump back wells and water treatment will be employed.

Freegold Ventures had a 10.362-m (34,000-ft) drilling program under way since July at the Idaho Almaden gold project in Washington County. The property, which Freegold holds a 100-percent lease interest in, is 21 km (13 miles) east of Weiser and was once the state’s largest mercury mine. The drilling, approximately half core and half RC. along with 1.212, m (4.000-ft) of large diameter metallurgical core, was designed to confirm the prior drilled resource, to upgrade the geologic database and to test for extensions of known hot springs mineralization. The property has a 43-101 compliant indicated resource estimate of more than 17.1 t (551,000 oz) at agrade of 0.72 g/t (0.021 oz/st) with additional inferred resources. More work is planned for 2007.

Kilgore Minerals commenced diamond drilling in July at its Kilgore property in eastern Idaho’s Clark County. Prior work from 1983 to 1996 by several majors outlined more than 14 t (450,000 oz) of gold in an indicated and inferred resource. Kilgore drilled the late Tertiary epithermal system and a newly discovered soil anomaly (Dog Bone Ridge) in 2004, intersecting high (3 m or 10 ft at 15.9 g/ t or 0.465 oz/st gold) and low grade gold mineralization in the Eisa Zone at some distance from the previous drilling. In 2006. Kilgore drilled 10 holes for a total of 3.323 m (10,902 ft). Strongly anomalous alteration and lower grade gold mineralization was intersected over a wide area.

Hell and High Water Mining trenched and sampled an interesting high placer deposit near the Edna Creek road north of Idaho City in the Boise Basin. The Boise Basin produced more than 72 t (2.3 million oz) of gold historically. Old hand placer piles of massive white quartz represent an unknown source for the gold on the placer claims. Closer to Boise. Desert Minerals apparently decided not to pursue its small cyanide milling operation at Blacks Creek in Elmore County.

Atlanta Gold held a public open house after its revised supplemental plan of operations was accepted by the Boise National Forest in mid-year. Work on the draft environmental impact statement was delayed due to corporate reorganizations. The company did raise $4 million in financing for the project. Some residents in Boise are concerned about the proposed mine’s potential impact on water quality of the Middle Fork of the Boise River.

Kobex Resources was in the middle of drilling two holes at the Cumo molybdenum deposit in Boise County, when the company returned the property to Mosquito Consolidated Gold Mines to pursue other interests. Discovered by Amax Exploration in the 1963, Cumo was extensively explored in the 1970′s. A 1982 Amax block model calculated an indicated resource of 1.3 Gt (1.4 billion st) of 0.093 percent MoS^sub 2^ at a 0.05-percent cutoff with a higher grade core to the multiple intrusive system. Mineralization is fairly deep but includes some copper. The 2006 program included two holes for a total of 3,560 m ( 1.085 ft), plus surface mapping. Mosquito reports that Hole 27 had 563 m ( 1.847 ft) grading 0.085 percent MoS^sub 2^ with mineralization from 40 to 564 m (130 to 1.849 ft) in depth. Hole 28-06 intersected 515 m (1,640 ft) grading 0.096 percent MoS^sub 2^. Mosquito plans to continue with additional infill and extension drilling.

State activities

Recipients of the 2005-2006 Idaho Department of Lands (IDL) Reclamation Awards included U.S. Antimony, Eric Wilson (IDL). Meridian’s Beartrack Mine, Kinross DeLamar Mining. Pat Trainor ( Fayette National Forest), Bruce Schuld (IDEQ), Monsanto, Nu-West Industries and Unimin.

The Idaho Geological Survey (IGS) continued an active geologic mapping program. New maps are released as digital web maps (DWMs) in pdf format on the Web site: www.idahogeology.org. Maps released included the Deadwood. Murphy and Orofino 100K quadrangle geologic maps. Long Valley surficial geology, geologic maps for Idaho Falls, Lewiston and Bonner County areas and the oil and Gas Exploration Drilling map. The IGS also had a research project under way on the Lemhi Pass Thorium District. More information is available for these and other survey activities on the IGS Web site or from staff.

V.S. GILLERMAN, member SME, E.H. BENNET and M.J. WEAVER, Idaho Geological Survey

Copyright Society for Mining, Metallurgy, and Exploration, Inc. May 2007

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