Monday, October 4, 2010

Key West Mine Property Examination 1932

This report came from the Nevada Bureau of Mines and Geology.  The original scan can be found here: 

Key West Mine, Clark County
Preliminary Examination Made January 23rd, 1932
By Alfred Merritt Smith

This examination was made in company with W.F. Darling, a rancher who lives on the Virgin River four or five miles north of the mine, and Jack Lisle, a prospector at that time living in St. Thomas.

The workings examined consisted of a tunnel about two hundred feet long, a cross-cut about one hundred fifty feet direct N. 50 W. Near the mouth of the tunnel is an incline fifty two feet long which connects with a drift running three hundred feet west, then seventy five feet south to a new shaft with head frame. The incline has a slop of about fifty-five degrees and also connects with the old shaft. About fifty feet in from the mouth of the tunnel is a drift running two hundred feet westerly on a vein two feed wide which splits and pinches out the face.

The country rock is a granitic or dioritic formation. It is intruded with a black igneous dyke apparently a peridotite formation, which has been mineralized and constitutes the ore body. The ore and dyke material contain augite, olivine, biotite and enstatite, pyrite, chalcopyrite, phyrrotite. The dykes are of pre-Cambrian age and are older than pegmatite dykes occurring in the area, which cut through both the black ore-bearing dykes and the granitic country rock.

The new shaft on the property is about three hundred feet deep. Water now stands in it at the one hundred and forty feet level. The shaft is said to have made twelve thousands gallons per day on the three hundred foot level. The water was said to be of good quality and potable.

The area is sparsely wooded with pinion, juniper and mountain Mahogany. The property is said to be owned by the Nevada Nickel and Copper Company, a corporation with offices at 50 Congress Street, Boston Massachusetts. R.E. Paine, 50 Congress Street, Boston is one of the officials known to the last operators.

The mine was last operated under lease and bond by a company represented by one Louis Thompson of Las Vegas and Los Angeles. Thompson had a lease and Bond on the mine and constructed a mill at an asserted cost of $120,000. J.J. Jessup was construction engineer. The mill was built in 1928 and operated for a time in 1928 and 1929. It contained an ore crusher, ball mill, Dorr duplex classifier, Wilfley tables and later, Grosh flotation cells. There is no doubt but what the mill was very poorly designed and was an utter failure. None of the group had any knowledge of modern metallurgy, yet they had the temerity to attack what is probably one of the most complex and difficult ores in the country.

Thompson stated to the writer that he shipped two hundred tons of concentrate to Los Angeles and about the same amount of ore. The concentrate was no better than the ore. Eleven hundred tons of ore was shipped to the International Smelter at Tooele, Utah, a hundred tons to the American Smelter at Garfield, Utah. A ton of matte (no information as to who produced the matte) was shipped to Stauffer Chemical Company, Richmond, California, and is said to have yielded good results.

Thompson said the value of the concentrate shipped was $119.00 per ton, some of even higher value. He stated that the ore contained copper – 6%, Gold – 0.02 ounces per ton, silver – 2.0 ounces per ton, platinum – 0.17 ounces per ton, palladium – 0.22 ounces per ton, nickel – 2.5 ounces per ton, cobalt – 1.5 to 4.0%, iron sulphide – 52%, silica – 12%. The ore contained no arsenic and no antimony.

Thompson organized the Key West Mining Company when he leased the property. He contracted many debts, was sued by creditors and a court judgment was obtained against him for $5,000. The creditors removed and sold the mill.

Locally Thompson himself is said to have incurred a majority of the bills and later on to have repudiated them, stating that he was only a minor stockholder in the Company. It was said, however, that he was a principal stockholder and is quite wealthy.

Gasoline engines were used for development work and to operate the mill.

Mt Darling stated that one of Thompson’s partner was named “Scoog”. The mill was removed in 1930.

The Tailings pond below the mill will average three feet deep and about 50 feet in diameter. There is also a pile of about twenty tons of concentrate.

The best ore in the mine is bunchy and erratic and results from the mineralization of the black igneous dyke in which it occurs, a most unusual ore occurrence. After being extracted from the mine the ore weathers and slacks after a time. The ore dyke in the Key West roughly follows the bedding of the gneissic country rock but spreads out along fractures on both the north and the south ends, forming seems and bunches. Most of the dyke is ore of lower grade. In the mine workings it appears to be from three to eight feet wide.

Prior to the operation of the mine by Thompson, it was owned by one Evans and Alfred A. Glaiser, who last worked it in 1904. The mine was discovered by a Cherokee Indian named Scott Allen about the Year 1890.

Some distance to the east and south limestone beds from 1,000 to 2,000 feet thick rise in cliffs resting unconformable upon the gneiss which is a country rock of this mine.

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