MICHIGAN ACADEMY OP SCIENCE. 95 



THE OCCURRENCE AND ORIGIN OF THE BROWN IRON ORES 

 OF SPRING VALLEY, WISCONSIN. 



R. C. Allen. 



Iron ores were discovered in the vicinity of Spring Valley in Pierce county, 

 Wisconsin, al)Out twenty years ago. Thorough prospecting developed a 

 number of deposits, two of which, known as the Oilman and the Cady de- 

 posits, are being mined. The Oilman was opened about 1890 and has been 

 in operation more or less continuously since that time. In 1893, a furnace 

 was erected at Spring Valley for smelting the Oilman ores and charcoal 

 ovens were built in the vicinity to supply fuel for the' furnace, but later, 

 charcoal was supplanted Isy coke as a fuel and the ovens went out of use. 

 The original plant has been ])artly replaced by a more modern one. The 

 furnace is 63 feet high by 7^ feet hearth and 13 feet bosh. There are two 

 blowing engines with a capacity of 14,000 cubic feet of air per minute, three 

 fire brick stoves 63 feet high by 17 feet drain with a chimney 150 feet high 

 by 7 feet drain, three batteries of two Cornish boilers each and a Mehan 

 uj^right water tube boiler* A considerable part of the ore which is used in 

 the furnace in obtained from the Mesabi and Penokee ranges, the remainder 

 being mined from the Oilman and Cady deposits near Spring Valley. The 

 furnace product is a non-Bessemer foundry iron varying from a thin low 

 silicon iron to a tliick high silicon iron. The slag is sold to the railroad for 

 ballast, for which it is excellent. Limestone for flux is obtained from a 

 riuarry seven miles nearly south of Spring Valley and brought to the furnace 

 by rail. The rock is a dolomite and contains, by analysis of a year's average 

 sample, dried at 212 degrees F: 



Fe SiO^ P Mn A 1,0 3 CaO MgO FeO 



'1.05 5.00 .015 .06 2.15 31.5 20.56 1.51 



The furnace, mines, and quarry are owned and operated by the Spring- 

 Valley iron and ore company, Frederick H. Foote, President and Treasurer. 



The Oilman Deposit. 



The Oilman deposit rests on an eroded, irregular .surface of the 

 Magnesian limestone, near its base, on the very upper slopes of a ridge above 

 the valley of a small creek triluitary to the Eau Oalle river. It is on the 

 C, St. P., M., ct O. Ry. railroad and is west of Spring Valley H miles. The 

 deposit is very irregidar in outline, as shown by the mine workings, Avhich 

 are open shallow excavations, the deepest being not more than 30 feet. 

 The ore is mainly a brown, hydrated hematite and occurs as nodules and 

 concretions mixed irregularly with ocherous clay, sand, and chert fragments 

 and nodular concretions of sand and clay. Locally, the deposit shows very 

 rough and irregular bedding but its general absence is con.spicuous. (Figure 

 1.) The limestone presents an uneven surface to the bottom and sides of 

 the deposit. In one place a wall of limestone some 6 feet or 8 feet high, 

 showing undoubted evidence of having been eroded while exposed to the air, 



*The writer is indebted to Mr. W. H. Foote, of Spring valley, for photograph--, details of plant and 

 a naly.ees here given. Mr. Geoige Fitzwilliams of Elv, Minne: ota, kindly furni.-hfd the analyse^ of 

 the Cady ores. 



