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New Ulm Quartzite Quarry Jenny Koester, Denise Weinkauf Stop #1a ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Figure 1a.A, Topographic map of the New Ulm Area, the stop is marked with an X marked quarries (http://www.terraserverusa.com/usgsentry.aspx?T=2&S=14&X=120&Y=1532&Z=15&W=1&P=120+km+SW+of+Minneapolis%2c+Minnesota%2c+United+States&D=01+Jul+1987&O=f44094a1&Lon=-94.4337&Lat=44.2944).
Location: New Ulm Quartzite Quarry, south east of New Ulm in Nicollet County, just south of Highway 14. SW Section 35, Township 110, Range 30 west. History of the Quarry: It is thought the quarry first opened in 1861, operations in the quarry were then shut down for 30 years, and became active again in 1956. The present company New Ulm Quartzite Quarries, Inc. is a private company that has been operating at the site since the reopening. The quartzite is mined for a variety of uses and products. Among the many uses are concrete aggregate, rip rap, railroad ballast, crushed road base, decorative landscape rock, crystalline poultry grit (http://www.nuqq.com/).
Figure 1a.B, This depicts part of the quarry operation (Courtesy of Toby Dogwiler).
Brief Description: Sioux quartzite is a purple to pink meta-sedimentary rock. The beds are well graded increasing towards the top, because of the increase in clay minerals. Secondary features include mud cracks, and crossbeds of clay minerals. Quartzite is massive at low grades and is coarser at high grades. The rock is hard and stable. In Depth: Quartzite is a hard rock with low porosity, and resists weathering making it an ideal rock for the economic purposes described above. The hardness of the Sioux quartzite (7) is a result of the mainly quartz composition (SiO2). The presence of quartz indicates that this area was once deeply buried as quartz does not weather chemically. Another mineral present in the Sioux is hematite which is responsible for the purple/pink color which is diagnostic of Sioux quartzite (http://www.nuqq.com/). Other trace minerals may be present but quartzite is 70-94% quartz (Austin, 1972). The age of the Sioux Quartzite is interpreted to be 1,470 MY. This date was determined by the Rb-Si of rhyolite bodies which are interbedded within the Sioux in a well which was drilled in Hull Iowa (Austin, 1972).
Figure 1a.C The obvious dip of this unit gives the perfect opportunity to practice taking apparent dip (Courtesy of Toby Dogwiler).
References: Austin, George S., 1972, The Sioux Quartzite, Southwestern Minnesota: Geology of Minnesota, A centennial Volume. Miller, Thomas P. A study of the Sioux Formation of the New Ulm Area. University of Minnesota, 1961. New Ulm Quartzite Quarries. http://www.nuqq.com/.11 November, 2003. Further Reading: Coath, Holm, Schnieder. "Age and deformation of Early Proterozoic quartzites in the Southern Lake Superior region: Implications for extent of foreland deformation during final assembly of Laurentia." Geology, v.26, no. 10; page 907-910. October 1998. |
