Tolovana

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag; As; Pb; Sb; W
Ore minerals arsenopyrite; galena; gold; pyrite; scheelite; stibnite; tetrahedrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0626
Longitude -147.4518
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Tolovana Mine is about 25 feet above Willow Creek at an elevation of 1,300 feet. It is approximately 1/8 of a mile upstream from the junction of Willow Creek and Cleary Creek, in the NW1/4NE1/4 sec. 25, T. 3 N., R. 1 E., of the Fairbanks Meridian. The location is accurate.

Geologic setting

Geologic description

Note: As of 2008, this site and several others in the vicinity are being explored as a single entity by Freegold Ventures Inc. (Freeman, 2008) Considerable new mineralization has been discovered that indicates this is part of a larger mineralized system that is described as a separate ARDF site (LG207).
The Tolovana Mine is an old property that was discovered before 1910. It operated intermittently until at least 1949, and was the site of considerable work in the 1980s. By 1910, an 85 foot adit had been driven at the Tolovana Mine. In July, 1911 a Huntington disc mill was installed and began operation on the prospect. The mill ran continuously through mid-November when lack of water forced it to close. The mill began operating again in March, 1912 after a well and pump had been installed on Willow Creek (Times Publishing Company, 1912). In July, 1912 a two-stamp Nissen mill was erected and began crushing ore on August 23, 1912.
In 1912, the mine consisted of a 400-foot adit from which several short drifts were driven; small stopes were also developed (Smith, 1913). The adit extends along the main shear zone for 130 feet where it intersects a vertical fault. (Note by compiler: In much of the early literature on this mine, the term 'shear zone' usually referred to a fault zone with parallel mineralized quartz veins, stringers, or pods, i.e., in other words what others here and elsewhere might have referred to as a sheared quartz vein or lode. The description that follows generally reflects the old 'shear zone' terminology. ) The workings turned north for 30 feet and then turn east again, along the offset extension of the shear zone. Approximately 100 feet from the portal of the adit, a winze was sunk to a depth of 50 feet and drifts were driven to the east and west. A second winze, inclined 60 degrees to the south, was driven from the east end of the drift but was flooded in 1912. A third winze, located 330 feet from the portal, was sunk from the adit level to a depth of 100 feet (Loftus, 1927). A shaft near the portal of the adit had been sunk to a depth of 100 feet and a drift driven on the 50-foot level connects with the winze in the adit. Due to the flooding of the shaft near the Tolovana adit in late 1912, work was shifted to the Willow Creek-Bedrock Creek divide where a 55-foot shaft, the Scheuyemere #1 shaft, was sunk on a 12- to 14-inch-thick shear zone (Times Publishing Company, 1912). This shaft is sometimes referred to as the Tolovana Stibnite prospect (Chapin, 1914).
By 1913, the shaft and the winze had been connected by a drift on the 100-foot level and the ore between the adit and the 100 foot level was mined (Chapin, 1914). Additional stoping took place above the adit level. By 1913, the Scheuyemere #1 shaft had been sunk to a depth of 100 feet and drifts were driven 50 feet to the east and 30 feet to the west on the 50-foot level (Chapin, 1914). A raise, 24 feet west of the shaft, connected with the surface and the block of ground between the shaft and the raise had been stoped from the 50-foot level to the surface.
In 1913, a new shear zone was discovered and shaft sinking was in progress (Chapin, 1914). This shaft, the South shaft, was connected to the Tolovana adit by a crosscut.
In 1922, the Tolovana adit was 530 feet long. A drift had also been driven from the 50-foot level of the winze for 30 feet to the east where it intersected a fault which offsets the shear zone (Stewart, 1922; Davis, 1922). In the South shaft, drifting at the 50-foot level went out 15 feet to the west and 20 feet to the east along the shear zone. A total of 150 feet of new drifting was completed on the Tolovana Mine in 1923 and 8 to 10 tons of ore were milled on site (Stewart, 1923).
The Tolovana mine was inactive until 1930 when exploration was renewed (Smith, 1933). The western extension of the Tolovana shear zone, on the west side of Willow Creek, was discovered in 1930 and was explored through the Parenteau adit (Stewart, 1931). This adit was driven 160 feet to the west ; 50 tons of ore was treated in the mill in 1930. The Parenteau adit was caved about 75 feet from the portal when visited in 1931 (Hill, 1933).
Antimony and gold were mined from the prospect in 1949 (Saarela, 1950). In August 1984, the Mine was explored by dozer and backhoe. A small gravity mill was constructed near the old portal of the Tolovana adit and several large open cuts were excavated in the vicinity of the Scheuyemere #1 shaft (Freeman, 1992). Surface samples from the Upper Pit area and the dump were also collected in 1986 (Fairbanks Exploration Inc., unpublished report, 1986).
Three types of metamorphic rocks are present at the Tolovana Mine (LeLacheur, 1991). The dominant rock unit is micaceous quartzite. Subordinate crenulated biotite-schist and a thin layer of amphibole-biotite schist are interlayered in the quartzite. Strongly altered plutonic rock is exposed in several trenches at the south end of the property (LeLacheur, 1991). The dominant process of ore deposition seems to have been replacement of the country rock and fault zones by quartz, sericite and sulfides, rather than quartz deposition in veins (LeLacheur, 1991, p. 50).
Initial development began on a series of 1- to 3-inch quartz veinlets with visible gold which trend N75E (Prindle, 1910). Ore in the Tolovana Mine varies from ribbon-texture quartz stringers to massive quartz veins which vary from a few inches to 3 feet in width. The mineralization had been traced for over 1,500 feet along strike. The 1- to 3-inch quartz stringers are separated by calcareous schist with disseminated pyrite. The gold-bearing quartz stringers contain euhedral stibnite but do not normally contain pyrite (Smith, 1913a). The gold through 1912, varied from 792 to 824 fine; the highest silver content was 180 parts per thousand from a sample with a gold fineness of 792 (Smith, 1913, B 525; Smith, 1913, B 542). Several generations of quartz have been noted; most of the gold occurs in the glassy quartz which postdates the more abundant milky-white quartz (Smith, 1913b).
A sheared vein was discovered in 1913, about 100 feet south of the portal of the adit; it strikes east and dips 50S (Chapin, 1914). The sheared vein is 18 inches to 36 inches wide and consists of massive white quartz with gouge along each contact. This vein is parallel to the shear exposed in the Tolovana adit. Shaft sinking was in progress in 1913. This shaft, referred to as the South shaft was later connected to the Tolovana adit by a crosscut.
The Tolovana vein (called a shear zone in the early literature) strikes N30-65E and dips 30-60SE (Smith, 1913, B 525, Smith, 1913, B 542). The western extension of the Tolovana vein was discovered in 1930 and was developed by the 160-foot Parenteau adit. The mineralization is in 1- to 12-inch-wide stringer zones similar to that mined from the Tolovana adit. The ore contained gold associated with arsenopyrite, stibnite, pyrite, galena and tetrahedrite (Stewart, 1933; Pilgrim, 1933).
The prospect was sampled by Fairbanks Exploration Inc. in 1986 (Fairbanks Exploration Inc., unpublished report, 1986). Backhoe and dozer trenches on the Tolovana prospect exposed a large section of metarhyolite tuff, exhalite, and volcaniclastic metaquartzite of the upper Cleary Sequence. These rocks contain disseminated and shear-zone-controlled arsenopyrite, pyrite, stibnite and native gold. The structures which hosted the high grade gold-quartz shear zones in the old Tolovana Mine trend predominantly N60-80E and dip steeply southeast; they transect the flat-lying, northeast-trending Cleary Sequence. Chip samples were collected in the Upper Pit across exposures of sulfide-bearing metarhyolite, cut by numerous 1-6 inch thick white quartz veins. Samples contained 520 to 3,600 parts per billion (ppb) gold. Samples from high-grade dump material at the small mill set up near the old Tolovana shaft contained 0.27 to 0.52 ounces of gold per ton. The samples consisted of white, massive, quartz vein material with 1-3 percent arsenopyrite and minor stibnite. The country rock welded to the sheared selvages is metarhyolite similar to that seen in the Upper Pit. As a check on the efficiency of the old gravity circuit in the Tolovana mill, a sample was collected from the tailings pond below the mill. This sample consisted of coarse sand-size material, 20-30 mesh in size; it was mainly quartz, arsenopyrite, pyrite and stibnite. A sample assayed 0.458 ounce of gold per ton. This suggested that the mill did a poor job of recovering the fine gold in the ore (Fairbanks Exploration Inc., unpublished report, 1986). In 1988 and 1989, Yukon Tanana Mining conducted extensive surface trenching on the Tolovana Mine and the adjoining Chechako prospects; the work outlined an estimated 150,000 ounces of gold that could be mined from the surface pit (R. Blakestad, oral communication, 1991).
Geologic map unit (-147.454247559116, 65.0621765966938)
Mineral deposit model Disseminated gold in quartz veins along shear zones.
Age of mineralization Probably about 90 Ma based on analogy with similar gold deposits nearby.
Alteration of deposit Pods and disseminations of jamesonite occur in an amorphous, green vuggy matrix in the walls surrounding the gouge zone (LeLacheur, 1991). Quartz, sericite, ankerite and carbon alteration also present.

Production and reserves

Workings or exploration
The Tolovana Mine is an old property that was discovered before 1910. It operated intermittently until at least 1949, and was the site of considerable work in the 1980s. By 1910, an 85-foot adit had been driven at the Tolovana Mine. In July, 1911 a Huntington disc mill was installed and began operation. The mill ran continuously through mid-November when lack of water forced it to close. The mill began operating again in March, 1912 after a well and pump had been installed on Willow Creek (Times Publishing Company, 1912). In July, 1912 a two-stamp Nissen mill was erected and began crushing ore on August 23, 1912.
In 1912, the mine consisted of a 400-foot adit from which several short drifts were driven; small stopes were also developed (Smith, 1913). The adit extends along the main shear zone for 130 feet where it intersects a vertical fault. (Note by compiler: In much of the early literature on this mine, the term 'shear zone' usually referred to a fault zone with parallel mineralized quartz veins, stringers, or pods, i.e., in other words what others here and elsewhere might have referred to as a sheared quartz vein or lode. The description that follows generally reflects the old 'shear zone' terminology.) The workings turned north for 30 feet and then turn east again, along the offset extension of the shear zone. Approximately 100 feet from the portal of the adit, a winze was sunk to a depth of 50 feet and drifts were driven to the east and west. A second winze, inclined 60 degrees to the south, was driven from the east end of the drift but was flooded in 1912. A third winze, located 330 feet from the portal, was sunk from the adit level to a depth of 100 feet (Loftus, 1927). A shaft near the portal of the adit had been sunk to a depth of 100 feet and a drift driven on the 50-foot level connects with the winze in the adit. Due to the flooding of the shaft near the Tolovana adit in late 1912, work was shifted to the Willow Creek-Bedrock Creek divide where a 55-foot shaft, the Scheuyemere #1 shaft, was sunk on a 12- to 14-inch-thick shear zone (Times Publishing Company, 1912). This shaft is sometimes referred to as the Tolovana Stibnite prospect (Chapin, 1914).
By 1913, the shaft and the winze had been connected by a drift on the 100-foot level and the ore between the adit and the 100 foot level was mined (Chapin, 1914). Additional stoping took place above the adit level. By 1913, the Scheuyemere #1 shaft had been sunk to a depth of 100 feet and drifts were driven 50 feet to the east and 30 feet to the west on the 50-foot level (Chapin, 1914). A raise, 24 feet west of the shaft, connected with the surface and the block of ground between the shaft and the raise had been stoped from the 50-foot level to the surface.
In 1913, a new shear zone was discovered and shaft sinking was in progress (Chapin, 1914). This shaft, the South shaft, was connected to the Tolovana adit by a crosscut.
In 1922, the Tolovana adit was 530 feet long. A drift had also been driven from the 50-foot level of the winze for 30 feet to the east where it intersected a fault which offsets the shear zone (Stewart, 1922; Davis, 1922). In the South shaft, drifting at the 50-foot level went out 15 feet to the west and 20 feet to the east along the shear zone. A total of 150 feet of new drifting was completed on the Tolovana Mine in 1923 and 8 to 10 tons of ore were milled on site (Stewart, 1923).
The Tolovana mine was inactive until 1930 when exploration was renewed (Smith, 1933). The western extension of the Tolovana shear zone, on the west side of Willow Creek, was discovered in 1930 and was explored through the Parenteau adit (Stewart, 1931). This adit was driven 160 feet to the west; 50 tons of ore was treated in the mill in 1930. The Parenteau adit was caved about 75 feet from the portal when visited in 1931 (Hill, 1933).
Antimony and gold were mined from the prospect in 1949 (Saarela, 1950). In August 1984, the Mine was explored by dozer and backhoe. A small gravity mill was constructed near the old portal of the Tolovana adit and several large open cuts were excavated in the vicinity of the Scheuyemere #1 shaft (Freeman, 1992).
The prospect was sampled by Fairbanks Exploration Inc. in 1986 (Fairbanks Exploration Inc., unpublished report, 1986). Backhoe and dozer trenches on the Tolovana prospect exposed a large section of metarhyolite tuff, exhalite, and volcaniclastic metaquartzite of the upper Cleary Sequence. In 1988 and 1989, Yukon Tanana Mining conducted extensive surface trenching on the Tolovana Mine and the adjoining Chechako prospects; the work outlined an estimated 150,000 ounces of gold that could be mined from the surface pit (R. Blakestad, oral communication, 1991).
Indication of production Yes; small
Reserve estimates In 1988 and 1989 Yukon Tanana Mining conducted extensive surface trenching on the Tolovana and adjoining Chechako prospects and outlined a reserve of about 150,000 ounces of gold that could be mined from a surface pit (R. Blakestad, oral commun., 1991).
Production notes Ore was shipped from the prospect as early as 1909 (Times Publishing Company, 1912). Production through 1912 averaged $20 to $105 per ton (1 to 5 ounces of gold per ton (Smith, 1913, B 525; Smith, 1913, B 542). In 1923, 8 to 10 tons of ore were milled on site, averaging $16 gold per ton (0.8 ounces of gold per ton) (Stewart, 1923). A small amount of ore was milled in 1924 and in 1931 (Stewart, 1923; Pilgrim, 1932; Smith, 1933, B 844). A little antimony and gold were mined in 1949 (Saarela, 1950).

References

MRDS Number A015430; D002659

References

Freeman, C.J., 1992, 1991 Golden Summit project final report, volume 2: Historical summary of lode mines and prospects in the Golden Summit project area, Alaska: Avalon Development Corp., 159 p. (Report held by Freegold Recovery Inc. USA, Vancouver, British Columbia.)
Freeman, C.J., 2008, Executive summary report for the Golden Summit project, Fairbanks Mining District, Alaska: Unpublished Technical Report for Freegold Ventures Ltd., 112 p. (posted on www.sedar.com, March 31, 2008).
LeLacheur, E.A., 1991, Brittle-fault-hosted gold mineralization in the Fairbanks district, Alaska: Fairbanks, University of Alaska, M.Sc. thesis, 154 p.
Pilgrim, E.R., 1933, Progress of lode mining in interior Alaska, 1932: Alaska Territorial Department of Mines Miscellaneous Report 194-4, 11 p.
Stewart, B.D., 1931, Report on cooperation between Territory of Alaska and the United States in making mining investigations: Alaska Territorial Department of Mines, Annual Report 1931.
Times Publishing Company, 1912, Tanana Magazine, Quartz Edition: Fairbanks, Alaska, Times Publishing Company, 76 p.
Reporters C.J. Freeman, J.R. Guidetti Schaefer (Avalon Development Corporation); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008