GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION
Up to about 1916, practically all of the molybdenite concentrates produced came from Queensland, New South Wales, and Norway. Shortly after the opening of the war, interest was shown in the production of molybdenite in Canada, principally in the provinces of Ontario and British Columbia. During 1917 and 1918 there was a great deal of interest in the United States in molybdenum ores, and at the present time this country can probably produce molybdenite concentrates in quantity equaling if not exceeding the rest of the world put together. Some molybdenum is produced by Spain and Peru.
Australia and Norway.
—The first official record of a production of molybdenite in Queensland was in 1900, when the output amounted to 12.3 short tons of high-grade material. The production gradually rose to 119 tons in 1906, and has not varied materially since that date, although the selling prices for concentrates increased considerably. The bulk of the material was mined at Wolfram Camp, in the Chillagoe field, 120 miles southwest of Cairns, in Northern Queensland. The mines at Bamford, in the same field, are credited with a small output. With the molybdenite ores are bismuth-tungsten ores, so that all three metals are produced.
The production of molybdenite was first reported in New South Wales in 1902; in that year the output was 17 short tons. The total output to the end of 1914 was 498 short tons, valued at $264,000. The chief producing molybdenite mines are at Whipstick, in the Pambula division, at Kingsgate, in the Glenn Innes division, and near Deepwater, in the Deepwater division. Molybdenite is also being produced at Rocky River, in the Tantafield division, and in the Bathhurst division. The production at all of these localities has not been large—in no one year exceeding 100 tons of concentrates.
In Norway, the production of high-grade molybdenite concentrates has averaged about 30 tons per annum since 1902. In 1906, an output of 1,129 short tons was reported. This probably refers to ore mined and not to concentrates produced.
The chief molybdenite districts in Norway are the provinces of Lister, Mandal, and Nedenes, on the extreme southern end of the peninsula. The district of Fjotland, in the former province, is probably richer in molybdenite than any yet discovered in Norway. A mine at Knaben, in this district, has been the largest and probably the only successful producer in Norway. This mine, owned by George G. Blackwell & Sons, of Liverpool, England,[94] has made an average output of about 25 short tons per annum.
[94] Reported taken over by a Norwegian company. U. S. Commerce Reports, September 24, 1918.
Table 33.—Production of Molybdenite in Queensland, New South Wales and Norway
| Year | Queensland | New South Wales | Norway | |||
|---|---|---|---|---|---|---|
| Weight (short tons) | Value (dollars) | Weight (short tons) | Value (dollars) | Weight (short tons) | Value (dollars) | |
| 1902 | 45.9 | 26,770 | 16.8 | 8,960 | 22 | 16,100 |
| 1903 | 26.9 | 10,220 | 32.5 | 21,960 | 34 | 21,400 |
| 1904 | 23.6 | 13,010 | 28.3 | 13,270 | 33 | 17,400 |
| 1905 | 70.8 | 41,340 | 21.7 | 12,200 | 51 | 16,300 |
| 1906 | 118.9 | 74,330 | 36.6 | 23,350 | 1,129 | 14,200 |
| 1907 | 74.0 | 41,080 | 24.2 | 17,340 | 33 | 12,900 |
| 1908 | 98.7 | 44,960 | 9.5 | 4,520 | 39 | 13,400 |
| 1909 | 103.9 | 45,120 | 31.5 | 15,810 | 33 | 12,100 |
| 1910 | 118.6 | 58,640 | 53.2 | 27,580 | ||
| 1911 | 111.4 | 64,610 | 23.1 | 12,610 | 2 | 800 |
| 1912 | 114.6 | 84,420 | 63.3 | 18,030 | 23 | 5,400 |
| 1913 | 74.3 | 92,460 | 88.3 | 33,100 | 13 | 3,200 |
| 1914 | 87.1 | 185,830 | 68.8 | 55,720 | ||
The production of molybdenite in Queensland, New South Wales and Norway, by years, is shown in the preceding table.
Figures for more recent years indicate the total production in Australia of about 330 short tons per annum and 110 short tons in Norway in 1916. In 1917 the output in Norway was three times the 1916 figures.
North America.
—As already stated, the chief molybdenite deposits in Canada are in the provinces of Ontario and British Columbia. They are low grade and of course need concentration. The Canadian and British governments have been much interested in the concentration of these ores and the Canadian government has a mill engaged in experimental work and in commercial concentration. The Department of Mines has spent a good deal of time in experimentation, believing that molybdenite has an important future in metallurgy.
The production in 1917 was about 80 short tons of high-grade concentrates and was undoubtedly larger in 1918.
Canada when properly prospected may produce a good deal more molybdenite than now.
In the United States are a very large number of small molybdenum deposits, scattered over the western states from Washington to Arizona and from Colorado to California. There are two common minerals—molybdenite, or molybdenum sulphide, and wulfenite, or lead molybdate. Generally speaking, molybdenite is found in the northern states, and wulfenite in the southern states, but this rule is not without exception. In Arizona and New Mexico, the principal mineral is wulfenite, but there are some fairly large deposits of molybdenite, probably the best being at the Leviathan mines, in Copper Canyon, Mohave County, Arizona. This is the only molybdenite deposit that is being worked in New Mexico or Arizona. It is in the Cedar Valley mining district about three miles southeast of Copperville and about 25 miles east of Yucca. This ore carries a good deal of copper, as well as small traces of gold and silver. Some analyses have shown 2 or 3 per cent. MoS2 and 1¹⁄₂ to 2 per cent. copper with 0.02 ounce of gold and 1 to 4 ounces of silver per ton. The percentage of molybdenite is undoubtedly above the average, which does not exceed 1 per cent. The country rock is medium-grained gray granite, consisting of quartz, feldspar, biotite, muscovite and small amounts of other accessory minerals, such as zircon and apatite. The company has erected a mill and has succeeded in making a satisfactory separation of the copper from the molybdenite.
The largest possibilities in Arizona and New Mexico are in mining wulfenite. This mineral is widely scattered over these two states, especially Arizona, and is, to a great extent, associated with vanadinite. One of the greatest difficulties in concentrating wulfenite has been the separation from vanadinite. The Bureau of Mines has worked on this problem for some time with partial success.
The most important deposit of wulfenite is at the Mammoth and Collins mines, in Pinal County. They were originally gold mines, and when the value of molybdenum became evident, Colonel Randolph, owner of the Mammoth mine, decided that it would be worth while to run the tailings dump for wulfenite. He converted his mill to this purpose, and not only ran the Mammoth dump but also the dump at the old Yuma mine, in Pima county. The total amount of concentrates produced by Colonel Randolph and others in the vicinity during the three years 1916 to 1918 are probably represented by 1,000 to 1,200 tons of wulfenite concentrates. While these operations were going on, they represented practically the only production of molybdenum concentrates in this country except on a very small scale. One other operating company is the Rowley Copper Mines Co., Gila Bend, Arizona, the ore being wulfenite and the principal impurity barite. The company has succeeded in making satisfactory concentrates, which carry, however, a considerable amount of barite. The Golden, Colo., station of the Bureau of Mines has run some tests on this concentrate and has made a partial separation of the barite and wulfenite.
Molybdenite is found in a considerable number of places in Colorado, Montana, Washington, Nevada, Utah, Texas and other western and northwestern states, but the largest occurrence is in Colorado. Generally speaking, the individual deposits in the West are not large enough to warrant the building of a mill for any one of them, and as the deposits are widely scattered, it is difficult to find a place where a custom mill could obtain a sufficient amount of ore. This is one of the chief difficulties in producing a large tonnage of molybdenite concentrates, outside of Colorado.
Probably the largest deposits of molybdenite in the world are at Climax, Colorado. These deposits are on the southwestern slope of Bartlett Mountain, Summit County, about 15 miles from Leadville. Outcrops are practically continuous across the whole length of the mountain and at places are one hundred to two hundred feet thick. The ore is rather granular and not flaky molybdenite, the average grade running about 8 per cent. MoS2.
There are two operating companies, the Climax Molybdenum Co., a subsidiary of the American Metal Co., of New York and Denver, and the Molybdenum Products Co., of Denver. Both of these companies have erected mills having daily capacities of 200 tons. The mill of the American Metal Co. started continuous operation about March, 1918, and that of the other company was completed shortly afterwards. Both companies claim that they can enlarge the capacity at short notice. The writer was in the mine of the American Metal Co. Evidently a considerable part of the mountain is molybdenite, and without doubt, a very large tonnage can be produced. The Jackling interests recently acquired the adjoining properties owned by the Pingree Mines Co., but in 1918 had not built a mill or carried out any serious development work.
Another very large group of deposits of molybdenite lies near Empire, Clear Creek County, Colorado, on the eastern slope of Red Mountain, at an altitude of about 11,000 to 12,000 feet. The deposits are 14 miles from the Empire station of the Colorado & Southern Railroad and are owned by the Primos Chemical Co., of Primos, Pennsylvania. The ore-bearing bodies consist of three veins of low-grade ore. The ore zone, that is, the ground included between the footwall of Vein No. 1 and the hanging wall of Vein No. 3 where cut by the tunnel, is about 200 feet wide. The veins vary greatly in width and are not particularly well defined, thin veinlets and stringers of ore running into the walls. The Primos Chemical Co. has worked these mines off and on for several years. About three years ago it built a mill near the mine, but production has been rather intermittent. This company has probably used all of its concentrates for making ferromolybdenum at its own works in Primos, Pennsylvania.
A small mill has been erected at Pitkin, Colorado, in connection with the mine at that place owned by the Pennsylvania Molybdenum Mines Co., of Johnstown, Pennsylvania. A number of other deposits of considerable interest are found in Colorado, especially around Breckenridge, Summit County. Here the pegmatite veins consist largely of muscovite and quartz, with some feldspar, and carry biotite, chalcopyrite and accessory minerals. The difficulty here is to separate the molybdenum from the copper minerals and also from the mica, most of which floats with the molybdenite.
Most of the developed molybdenum deposits of Mexico are in the State of Sonora. In the Sahuaripa district of eastern Sonora, the mineral occurs with scheelite in rich pockets containing very large pieces of pure mineral. Some molybdenum ore has been shipped from the Montezuma copper district to the Empire Smelting & Refining Co., of Deming, New Mexico. Molybdenum is reported in several other Sonora localities. Near Coyame and Marquez, northeastern Chihuahua, the mines of the Compañia Minera Aurora y Anexas produce molybdenum ore. Wulfenite is found abundantly with the lead ore of the Cuchillo Parado mine in the same district. The Jibosa copper mine of the American Smelters Securities Co., near Jimenez, Chihuahua, seems to carry considerable oxide of molybdenum, molybdite. It is not commercial at present.
Molybdenite deposits are also reported in the states of Sinaloa, Oaxaca, Hidalgo, and Jalisco.