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VIRTUAL FIELD TRIP TO THE KEWEENAW PENINSULA, MICHIGAN - MINING HISTORY (1920-1995)

     The period after 1920 saw the mines enter into a period of decline. After the First World War, there was dumping of copper onto the market, copper demand was down, and the western mines relied more and more on open pit mining. Each pound of copper produced meant that there was one less pound of copper to mine and the costs of mining kept increasing as the ore deposits increased in depth and the ore grades dropped. It was often cheaper for the mining companies to reprocess the tailings from earlier operations than to mine new ore. They kept active until the 1960's, but were a high cost producer of copper. Whenever the price of copper declined, the mining operations would slow and some mines would close, never to reopen.

   In the area of milling, the companies started using the Wifley tables which captured smaller particles of copper. The mining companies also dredged the older stamp sands which still  contained about 25% of the original copper. These were then ground finer in ball mills (giant rotating cylinders with balls of iron to crush the sands). They also used froth flotation which used chemicals and air to concentrate the copper in the bubbles, which were then skimmed off from the waste rock stream. Processes were developed to dissolve the copper in ammonia and recover the copper from these solutions.

    The White Pine mine was first prospected in 1865. The fine grain size of the copper minerals precluded any development of the mine at this time. Calumet and Hecla mined the property for native copper from 1909 to 1921. The Copper Range company outbid Calumet & Hecla in a 1929 sheriff's sale by  $388.15 and obtained the mine. During the Korean War, they obtained a $68 million loan to put the mine back into operation. They were able to use a room and pillar method (since the deposit is relatively flat) to develop the mine. The White Pine mine was producing from 1952 to 1995 when the smelter could not reach environmental standards. In 1997, plans to solution mine copper were also shelved due to environmental concerns.  It was an unusual ore body for the district in that there was significant production of copper sulfides (primarily chalcocite) and the copper was found in the Nonesuch shale, a formation that was deposited after the lodes in the rest of the Keweenaw. The mine produced over 4 billion pounds of copper and 45 million ounces of silver.

   The other sulfide ore body in the area is in the Mount Bohemia area on the far north side of the peninsula. A number of copper sulfides are found in an igneous porphyry body. A number of attempts have been made to mine this ore, but none have been successful. The area is now a ski hill.

     Calumet & Hecla had attempted to stay in the copper mining business by purchasing control of other smaller mines in the district as well as exploration for other ore bodies on their properties. A strike in 1968, the sale of the Calumet & Hecla company to Universal Oil Products, and the lesser grades at greater mining depths caused the shut down of the mines. In 1970, the company stopped the pumps on it's Centennial and Kingston shafts, and the last native copper mines shut down. A large percentage of the production in later years by C&H was recovery of scrap and reprocessing of the tailings from earlier mining. The stamp sands were recovered from Torch Lake with the use of a dredge - later purchased by the Quincy mine ( It is still sitting in the lake). 


Quincy #1 dredge on Torch Lake. Dredge sank on 1/15/1956.Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Negative 03808 from Louis Koepel / Quincy Mining Company. For present day view click on photo above.


Even though mass copper was relatively rare, even in the later mining period some was found. Power equipment made handling the masses somewhat easier, but it still required greater handwork than the normal ore. 12th level of the Ahmeek mine, with the mass partially reduced. Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #137.


Calumet & Hecla #6 at the 62nd level stope. The extreme pressures at depth cracked timbers used to keep the stopes open.  Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #9


Tamarack #5 shaft - Rock house breaker floor. The rock house allowed rock being brought to the surface to be processed. Underground, the ore from the stopes was segregated from waste rock generated to tunneling to reach ore-bearing areas so that they could be raised to the surface separately.  Any waste rock could be shunted directly to rail cars for disposal on surface waste rock dumps which were located near the mine shaft. Ore from the mine was passed over the grizzly (on the right) which allowed the smaller rocks to pass through directly to the ore cars for transport to the mills. Larger rocks were fed into crushers to the left. Any relatively pure pieces of copper were pulled off so that they would not break the crushers and were sent directly to the smelter. Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #124


20x24 steam stamp. The steam powered cylinder was at the top of the machine. The head (on the bottom) would have a metal trough that surrounded it, and there would be an automatic feeder for the ore. The pulverized ore would go on to further processing in jigs and sand wheels or Wifley tables. Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Negative 05238.


Osceola mill jigs. Jigs were used to separate larger pieces of native copper from the waste rock by gravity.  Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #316.


Wifley tables on the Ahmeek mine were used to separate native copper of a relatively small size (sand) from the waste rock. These replaced the earlier sand wheels. Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #296


Wifley tables? Photo courtesy Michigan Technological University archives and Copper Country Historical Collections.


Calumet & Hecla smelter's electrolytic plant. Copper was purified by dissolution of the partially refined copper and electroplated on electrodes. Photo courtesy Michigan Technological University archives and Copper Country Historical Collections. Calumet & Hecla photograph collection MS-003 Box 25 #332.

Caledonia mine on south end of range. Mine started in 1863 and is the last active mine on the peninsula (mining is for specimen material).

Nebraska mine. Slotted doors allow bats to enter and leave the mine (they live and hibernate in the mine) while keeping people from entering (2001).