U.S. MINING REPORT — Carolina Slate Belt draws attention of

The discovery of a 17-lb. gold nugget in Cabarrus Cty., N.C., in 1799 heralded the first U.S. gold rush. It quickly led to the first thriving gold-mining camp of the Slate Belt and the first in the country in the early 1800s (until the 1849 California gold rush lured virtually all the eastern miners away).

The revival of this ancient camp, however subdued, is attributed to several factors:

* well-developed infrastructure;

* familiar geological conditions (for Canadian Shield explorationists in particular);

* favorable exploration climate;

* low local labor rates;

* availability of all necessary services; and

* reasonable demands concerning environmental compliance.

Furthermore, the Slate Belt offers a vast potential, barely tested since the early days, and the lure of elephantine, Hemlo-like orebodies. The fact that fee lands must be leased from individual owners has proved to be no hindrance, particularly to explorers of public lands faced with the prospect of the drastic overhaul of the Mining Law of 1872. The terrain also allows the use of simple and relatively inexpensive exploration techniques which can often prove more rewarding than complex technologies. The Carolina Slate Belt lies like a pea inside the giant pod of the Appalachian trough, which stretches from Alabama to Newfoundland. Lying in that trough are such legendary deposits as Ducktown, Ridgeway, Haile, Gossan Lead and Brunswick 12.

The 600-km-long and 100-km-wide Slate Belt itself is the locus of 1,500 mines which, from 1820 to 1934, produced more than 1.5 million oz. gold. Another 1 million oz. have been produced since 1985 from only four mines. After painstakingly exploring the Slate Belt for more than a decade, D.J. LaPoint and C.H. Cherrywell detailed the variety of deposits to be expected — from Ridgeway-Haile, silicified, gold-moly-pyrite models to shear-zone-hosted and massive-sulphide-related mineralized bodies. Evidence of placering for gold is common in the Belt, but the presence of clay precluded efficient recovery. Fortunately, the evolution of the art of agglomeration has transformed heap leaching into “trickle leaching” by creating controlled porosity. Hence, the dissolution of gold by cyanide solution is considerably improved, in terms of time and recovery. This method affords geologists a new perspective on neglected tracts of mineralized saprolite.

The focus of activity remains the Uwharrie-Tillery contact, a key horizon on or near which the most productive gold mines in the region are situated. It may prove to be to the Carolinas what the Larder Lake Break was to mining in Ontario.

On this contact lie the celebrated Haile and Brewer mines, gold producers for more than a century. On the projection of the same contact lies the more recently developed Ridgeway mine, the major gold producer of the eastern U.S. Today, there are four notable gold producers in the Slate Belt: Ridgeway, Haile, Brewer and Barite Hill.

The Ridgeway mine in Fairfield Cty., S.C., was placed in production in 1988 by RTZ (NYSE) and Galactic Resources (TSE). It is now halfway through its original 56 million tons of reserves, with current reserves totaling 28 million tons of 0.03 oz. gold per ton. It produced 137,000 oz. in 1993 at an average cost under US$200 per oz. Yearly production to the end of its life in the year 2000 will average 110,000-120,000 oz. The mill’s throughput of 16,400 tons per day is equivalent to moving 12-14 million tons of material per year, with a waste-to-ore ratio of 0.74-to-1.

Gold was first mined in 1829 at the site of the Haile mine of Lancaster Cty., S.C., which continued in operation until forcibly closed in 1942. It was brought back to life by owner Piedmont Mining (NASDAQ) to produce 85,000 oz. gold from 1985 to 1991 through the use of heap leaching. A new drilling program, launched in 1990, outlined 13 million tons grading 0.091 oz., of which 7 million tons grading 0.1 oz. were deemed minable by open pit. Besides the existing eight open pits on the 3,700-acre property, the new discovery zone, recently investigated by vertical holes, revealed several gold-bearing intersections. These include 0.112 oz. over 205 ft. and 0.414 oz. over 115 ft. Operator Amax Gold (NYSE) will shortly release the latest reserve figures. The Brewer mine of Chesterfield Cty., S.C., was worked extensively from 1844 until it was shut down by wartime emergency measures in 1942. A considerable tonnage of ore averaging 0.15 oz. was extracted. Exploration work in the 1980s was pursued by Brewer Mining, and 4 million tons grading 0.042 oz. were treated in an exceptionally fast (21 days) and high-yield (88% recovery) leaching program.

Consolidated Nevada Goldfields (NASDAQ) started producing at Barite Hill in McCormick Cty., S.C., in 1990 and treated 70,000 tons monthly to recover 15,000-20,000 oz. gold yearly. The ore extracted from two pits is coming to an end within a year, but several satellite bodies have been identified. About 20 companies, large and small, have explored the Slate Belt in the past decade, including Inter-Rock Gold (ME) and Minefinders (VSE). The former has announced a program to follow up on the 1990-92 exploration work carried out on the Jefferson prospect in Chesterfield Cty. The work will focus partly on the ancient Leach mine, adjacent to the Brewer pits. Four mineralized zones were previously identified by 18,500 ft. of air rotary drilling. Extensively mineralized intersections (some of Ridgeway grade) were reported from a program of 17 core holes. Another 6,000-10,000 ft. of core drilling are planned, together with geochemical work and overburden-saprolite delineation over the 1,112-acre property.

After completing 5,100 ft. of drilling, Minefinders plans to start another reverse circulation hammer drill program, on the Sawyer gold mine in Randolph Cty., N.C. The mine contains 1.65-3.3 million tons of geologically inferred reserves with an average grade of 0.5 oz. The bulk of the deposit lies from surface to an average depth of 75 ft. in clay and saprolite. — Jean-Claude Leroy is a geologist and writer in Toronto.