Mining Claims

History of the Deer Trail Claims

Geological Reports

1997 Report
- Geology of the Manto Deposits
- Orebodies
- Areas of Economic Potential
- Recommendations

1998 Report
- The 3400 Area
- The 8600 Area
- Conclusion

2002 Report
- Deer Trail Estimated Resources

Mine History

Deer Trail Mine History

1997 Report

APRIL 1997 - Geographical Resource Evaluation of the Deer Trail Mine
Piute County, Utah

The Deer Trail Mine in Sevier County, Utah, near Marysvale is located near the center of the Marysvale volcanic field in the High Plateaus of west-central Utah. These high plateaus form a transition between the Colorado Plateau and the Basin and Range Provinces, and consist typically of relatively flat-lying sedimentary and volcanic rocks that have been broken by late Cenozoic extensional faulting into elongate north-trending mountains separated by narrow alluviated structural troughs.

The mine is located at the eastern base of the Tushar Mountains, which form one of the main horst blocks in the High Plateaus in this vicinity. The Deer Trail ore was first discovered by deer hunters in 1878. Over 10,000 tons of ore were produced prior to the turn of the century, which is reported to have assayed over an ounce of gold per ton. The mine again produced from 1918 to 1923. Approximately 140,000 tons of ore were mined and treated. Nearly 200,000 ounces of gold and well over 1.5 million ounces of silver were produced from this period of production from what is now know as the Old Deer Trail Mine. This ore was primarily oxidized ore. In the late 1950s a new tunnel (PTH Tunnel was put in approximately 400 feet lower and south of the Old Deer Trail Mine. This tunnel extends nearly 10,000 feet into the mountain. Ore at the Ontario Mine in Park City, Utah was concentrated and sent to a smelter in Kellogg, Idaho for settlement. Over 100,000 tons of ore were produced from the PTH Tunnel. Mining was halted due to the closure of the Park City facility and Kellogg smelter. Since that time Phelps Dodge, Noranda and goldfields mining companies have conducted exploration programs at the mine and surrounding areas.

Geology of the Manto Deposits [ return to top ]

The Deer Trail Mine workings expose westerly dipping sedimentary rocks of three units: The Toroweap, Quantoweap Formations and Caville Limestone. The Deer Trail ore bodies are in the lower part of the Toroweap Formation and consist of nearly continuous groups of semiconcordant replacement bodies, i.e. mantos, flanking a central vein. About half of this orebody is exposed in the Old Deer Trail gold mine workings, which is completely oxidized; the other half is located in the 8600 area working in the PTH Tunnel and consists of unoxidized sulfide ore. The Queantoweap Formation which underlies the Toroweap is a quartzite bed and does not host any known mantos. The underlying Callville Limestone contains the orebody uncovered in the 3400 area in the PTH Tunnel.

The principle sulphide deposits exposed in the Deer Trial Mine, form a semi-continuous group of elongated strata-bound Pb-Zn-Ag-Au-Cu bodies (mantos) that replaced as many as 15 carbonate beds in the lower part of the Permian Toroweap Formation. The mantos are stacked along a prominent, steeply dipping axial vein and thin symmetrically away from it. Where unoxidized, individual mantos consist almost entirely of sulfides (pyrite-galena-sphalerite-chalcopyrite), have sharp contacts with the country rocks and range from <2 feet to 9 feet in thickness.

The deposit formed during the interaction of two types of heated aqueous water was significant during main-stage base metal mineralization, but was replaced almost entirely by meteoric water in late stages of the host mineral paragenesis.

Approximately three quarters of a mile west of the mantos, an area of hydrothermally altered rock coincides with a domed area cut by radial fractures, suggesting a hidden intrusion at depth. The Deer Trail deposits are part of a halo of metallic deposits that surround this altered and deformed core.

Many geologic and geochemical relations at Deer Trail are similar to those in a number of the economically more important manto deposits in the western United States (Tintic, Park City, Leadville, Gilman, Pioche), which by analogy may have had a similar origin.

Orebodies [ return to top ]

The Deer Trail 8600 area orebody consists of a group of individual mantos that flank a north-westerly trending, steeply dipping vein called the Red Fissure. Individual mantos are strata-bound, attaining a thickness of as much as 10 feet. The manto ore is typically thickest at its intersection with the Red Fissure. Some of the thicker manto orebodies (206 stope) split at their margins into several tongues, that in turn wedge out. As seen in at least two localities (202 raise and 206 raise), where a large vertical section is exposed, several mantos are bi-laterally symmetrical about the Red Fissure. In various stopes of this area, at least 15 different mineralized beds have been exposed in the loser 120 feet of the 300 foot thick Toroweap Formation. There is a tendency for individual orebodies to replace successively higher beds in the section westward along the trend of the Red Fissure.

A set of cross faults that trend east-northeast and dip steeply to the north are exposed in this area. These have an aggregate stratigraphic throw of about 150 feet, down to the north. One of these faults is the 18 drift fault. These faults are now occupied by quartz veins as much as 15 feet thick that contain substantial quantities of Pb, Zn, As, Au, and Mo.

The 3400 area orebody is oval shaped in plain view and measure about 200 feet by 390 feet across. Although at least six strata-bound mineralized zones have been identified in the underground workings, only one has the right combination of grade and thickness to have been mined. The 3400 area is cut by a number of high-angle faults which strike both northeast and northwest. Many of these steep faults are now occupied by thin oxidized braided veins. The veins and mantos are commonly contiguous and merge with one another. Strata-bound and fissure mineralization thus appear to be contemporaneous. The strata-bound ore is typically higher in grade than the vein ore, although some veins are relatively rich in silver.

In the lower workings (PTH Tunnel), records show that of 69,934 tons produced between 1960 and 1971 averaged 0. 071 oz. Per ton Au, 8.41 oz. Per ton Ag. 5.7 1 % Pb 8.28% Zn and 0. I 1% Cu (current value $201 per ton). The PTH Tunnel was driven to intersect the down-dip projection of the mineralized bedding mined in the upper Old Deer Trail workings. The tunnel unexpectedly intersected a mineralized horizon at 3,400 feet, and finally intersected the target bed at 8,600 feet. Ore was produced from both areas. Below is the average of the ore remaining in the PTH Tunnel workings based on samples taken by Phelps Dodge, Noranda and Goldfields.

One sample from the 8,600 area 100 level assayed 0.028 oz. per ton Au, 991.66 oz. per ton Ag, 1.05% Pb, o.74% Zn and 6.4% Cu. Another sample from the 3,400 area tunnel level assayed 4.0 oz. per ton Au and 0.28 oz. per ton Ag.

Over one million tons of ore is estimated to be contained in the two mineralized beddings in the mine. However, Noranda drilled through yet another mineralized horizon approximately 200 feet below the present working at the 3,400 area. This ore is valued at over $200 per ton. Ore is still present in the majority of the faces of the PTH workings.

The upper Old Deer Trail working contain very prospective zones of gold bearing oxide ore. This material is seritically altered with a fair amount of clay. The clay combined with the sericite historically yielded poor recoveries due to slimes. Advances in leach technology since the late 1800s will produce higher precious metal recoveries from this type of material.

Goldfields Mining Company collected over 83 samples from the underground workings in the Old Deer Trail Mine in 1988. These samples averaged .116 opt Au and 2.55 opt Ag. Noranda Mining Company sampled the same area in 1986 which averaged .135 opt Au and 3.18 opt Ag. It estimated that over 400,000 tons of the above mentioned mineralized rock is present in these upper workings. Also, approximately 123,000 tons of mineralized mill tailings averaging .04 opt Au and 8.0 Ag are present on the surface of the old Deer Trail Mine.

Areas of Economic Potential [ return to top ]

The most logical locality for economic potential lies within the workings of the Old Deer Trail Mine. Goldfields' geologist recommended this to be mined as an open pit in 1988 due to the unusually high gold values found throughout the workings combined with good evidence of expanding the known resource. However, it was deemed by engineering that open pit mining would be limited by high-wall problems on the western portion of the deposit. Several overlying horizons are very favorable to mineralization and could greatly increase the economic potential of this area.
The beddings containing the many mantos of the PTH working have had little development and hold great potential. Also, the eastern continuation of the Callville Limestone has every chance of containing mineralized replacements along the axis of the Deer Trail anticline, thus increasing the potentially economic base metal resource.
Very little mention has been made of the alteration west of the Deer Trail workings (within the boundaries of Unico's property), which could contain a repeat of the same grades and thickness as the Deer Trail deposit.

Recommendations [ return to top ]

It is recommended that a drilling program be designed to establish mineable reserves in the Old Deer Trail workings. Leach tests should be done to ascertain the most cost effective method of recovering the metals from the ore. It is also recommended that a deep hole be drilled to confirm the third mineralized horizon discovered by Noranda. This property has great potential as both a gold-silver and base metal producer. The property position of Unico is more than sufficient to cover the mineralized zones. The mine has excellent infrastructure i.e. electrical power, good roads and well maintained underground workings complete with ventilation and water.