Common Minnesota Rocks | College of Science and Engineering
It is the intrusive equivalent to basalt. Minnesota's best examples of gabbro are in the part of the 1.1 billion-year-old Midcontinent Rift exposed in the large hills in and north of Duluth, known as the Duluth Complex. The rock is dense, dark-colored, and contains varied percentages of the minerals plagioclase, pyroxene, and olivine.
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