Yerington Mine
The Yerington portion of the complex is comprised of 108 unpatented lode claims, 85
patented lode claims, fee lands totaling 1,547 acres and 21 mill site claims, cumulatively
totaling approximately 4,500 acres as depicted in Figure 1. (available on request) There
are no outstanding royalty interests.
Copper oxide ore is processed at the Yerington mine site by crushing and acid curing
followed by heap leaching. Approximately 21 million square feet of leach pad area is fully
permitted. Leach solutions are processed at the on-site SX-EW plant (built in 1991) that
is capable of producing up to 63,000 pounds of high-grade electrolytic cathode copper per
day. Warehouses, a carpentry shop, metal shop, repair shop, garages, main office, mine
office, assay lab, and chemical lab are on site. The mine/plant facility is located near
the town of Yerington, Nevada, approximately 80-road miles southeast of the city of Reno,
Nevada. Paved highway Alternate 95 passes just east of the existing Yerington open pit.
Electrical power is currently available at the site by Sierra Pacific. Arimetco has one
main water well and 5 make up wells that are more than sufficient for projected
operations.
History - The first production of copper in the Yerington district was recorded in the
early 1900's. Initial exploration on the present Yerington Mine was carried out by a
subsidiary of the Anaconda Company in the early 1940's. This work delineated a reserve of
60 million tons at 0.90% to 0.95% Cu comprised of 40 million tons of oxide ore below which
were 20 million tons of sulfide ore. Development of the Yerington ore body was postponed
for a number of years because of anticipated high production costs. A positive production
decision was made in 1951 and the Yerington deposit went into official production in late
1953.
Between November 1953 and June 1978, the Yerington operation produced 162 million tons
of 0.55% Cu from a single pit which is now approximately 6,400 feet long by 2,800 feet
wide by up to 500 feet deep.
Anaconda shut the mine down in 1978 due to a combination of low copper prices and low
profit margins on the sulfide ores.
In 1982, Don and Joy Tibbals purchased the property from Atlantic Richfield Company,
successor to Anaconda.
In mid 1989, Arimetco International Inc. purchased the property and a SX-EW plant was
commissioned by Arimetco in 1991.
Vat leach tails and oxide stockpile material is currently being processed on-site at a
rate of approximately 40,000 tons per day.
Geology - The Yerington Mine is a typical porphyry copper deposit. Oxide and sulfide
mineralization occurs in Jurassic quartz monzonite, quartz monzonite porphyry and
granodiorite host rocks. Chalcopyrite, bornite, and chalcocite are the principal copper
minerals in the sulfide zone. Chrysocolla is the common oxide mineral. The ore body is
largely overlain by Quaternary gravels and limited to the west by Tertiary volcanics.
Mineralization is related to two porphyry intrusions in a sequence of pre-and post-mineral
dikes.
Reserves - The Yerington Mine contains both oxide and sulfide reserves. The oxide
reserves include drill proven and probable 62 million tons at a grade of 0.17% copper
within which there are 14 million tons of oxide ore at a grade of 0.32% copper in the main
Yerington pit and 48 million tons of Vat Leach Tails (VLT) grading 0.12% copper. The
sulfide reserves include about 610 million tons of probable and possible reserves at a
grade of about 0.39 % copper within which there are 84 million tons of 0.361 % copper
within the old Yerington pit, 4 million tons of 0.30% copper in the S-23 stockpile, 22
million tons of 0.296% copper adjacent to the old Yerington pit and 500 million tons of
0.40% copper in the Bear zone northeast of the pit. Five million tons of mixed
oxide-sulfide grading 0.15-0.20 % copper are in the W-3 dump. Contained metal within the
Yerington mine is about 5 billion lbs. of copper. The VLT ore has an 80% recovery rate in
60 days. The W-3 stockpile or! e has a 50% recovery rate in 6 months and can yield another
10% for 2 additional years for a total recovery rate of 70-80%. Metal is currently being
recovered at 2.4 to 4.0 lbs. per ton. There is no stated cut-off grade as all material is
mined.
Operations - Ore is being processed by acid leach on prepared pads at a rate of 40,000
tons per day. The recovery method is SX-EW and final product is in the form of cathode
copper plates. In October 1998, Arimetco processed 1,135,766 tons of ore and 2,271,532
lbs. of Cu. Major machinery (trucks & dozers) is being efficiently utilized at greater
than 85% of availability (See the equipment list attached as Attachment 1). Cash costs for
the first half of 1998 were US $0.66 per pound of copper recovered. Cash costs for August
- October 1998 ranged from US $0.71 - 0.74 per pound of copper recovered.
Employees: There are 56 employees (10 salary, 46 hourly) comprising the current work
force. The mine operates 20 hours per day 6 days per week.
Mine Life: At the rate of 12,480,000 tons per year, there is a 3.8 year mine life for
the VLT ore and 0.4 year mine life for the W-3 stockpile. (cumulative total mine life is
approximately 5 years).
Permitting/Reclamation Liability - The Yerington and MacArthur deposits are fully
permitted; however, the Nevada Department of Environmental Protection requires that
Arimetco's corporate guarantee be replaced by a reclamation performance bond or similar
surety instrument.
The state has preliminarily indicated to Counsel that it will cooperate with Arimetco's
successor to minimize the reclamation liability to which an incoming party would otherwise
be subject under similar circumstances.
With respect to Yerington, the property is subject to an order issued against Anaconda
relating to the discharge of pollutants into the ground water in and about the Yerington
Property issued by the State of Nevada Department of Conservation and Natural Resources,
Division of Environmental Protection. Pursuant to this order, Atlantic Richfield Company
was required to drill monitoring wells in the north portion of the property in order to
monitor ground water conditions within the Yerington Property. Such wells are currently
being monitored by ARCO.
MacArthur Mine
The MacArthur Mine is a fully stripped and permitted porphyry copper property with a
drill proven resource of 29 million tons grading 0.28% Cu and 162 million pounds of
contained metal. The property is comprised of 76 unpatented lode claims covering
approximately 1,150 acres in a contiguous block as depicted in Figure 2.
Arimetco gained a 100% interest in the property in 1990, amended its Plan of Operation
to include a 4.5-mile haul road (thus eliminating the need for separate leach pads and
ponds) in 1993, and commenced commercial production in 1995. During 1995, the mine
produced 687,000 tons of ore. In 1996, the mine produced 3.84 million tons of ore. There
was no production until the fall of 1997 when the mine produced approximately one million
tons of ore. It is thought that production ceased as a result of excessive haulage cost
from the mine to the SX-EW plant.
Geology - The MacArthur deposit is hosted in Jurassic Bear quartz monzonite which has
been intruded and mineralized by a complex series of northwest trending dikes.
Mineralization consists of copper oxides and silicates, copper wad, and iron oxides.
Reserves - The MacArthur deposit has 29 million tons of drill proven reserves with an
average grade of 0.28% Cu. Metal is recovered at a rate of 85% for the acid cured material
and 45%-75% for the remaining ore. The deposit contains about 140 million pounds of
recoverable metal. The cut-off grade at an assumed Cu price of US$1.00 per lb. is 0.16%.
Operations - Prior to November, 1997 when the mine was shut down due to Arimetco's
increasing financial difficulties, Arimetco was mining at the MacArthur Mine and
processing the ore by acid leach on prepared pads at a rate of 40,000 tons per day. The
recovery method used was SX-EW with copper cathode plates as the final product.
Ann Mason Deposit
The Ann Mason deposit adds to the overall resource at the Yerington Complex and is
comprised of 74 unpatented claims totaling 1,385 acres as depicted in Figure 3. The
deposit is located approximately 3 miles west of the Yerington Mine. The Ann Mason
deposit, which was discovered in 1971, has been delineated by more than 133,000 feet of
core drilling in 103 drill holes, with the central portion drilled on 200 foot centers and
the exterior portions more widely spaced. At a cut-off of 0.03% copper, the deposit
contains a drill proven and probable resource of 495 million tons of ore at a grade of
0.4% Cu, stripping ratio of 3.5:1 overall, and recovery rate of 90% by flotation. A full
feasibility study has not yet been completed to determine the copper price at which the
Ann Mason deposit is economic.
Geology - The Ann Mason deposit is a Jurassic porphyry system localized at or near the
contact of a Jurassic quartz monzonite mass intruding granodioritic host rocks. A complex
series of mineralized quartz monzonite porphyries are the primary hosts for the copper
mineralization. Ore minerals are primarily chalcopyrite and bornite with pyrite.
Exploration Potential - There is potential for the existence of a 100 million ton high
grade, 0.5% copper core to the west and northwest under volcanic cover. To date, the Ann
Mason deposit has not been permitted and no work has been completed to advance the
property to production.
A serious statement of interest should be made through ICON LAND SERVICES, INC. no
later than February 15, 1999. If this is of interest to you, please autoreply
through the MineMarket.com Information Request.
