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The mine has a steady decline plunging to 1,774 feet below sea level. The mine is the deepest point in the United States where a car can be driven, down a ramp used by specialist mining vehicles. In 2022, Eagle Mine was used to set a Guinness World Record for the greatest altitude change achieved by an electric vehicle. [1] [2]
Name County Years Material Coordinates Adventure mine: Ontonagon: 1850–1920: copper: Alabastine Mine: Kent: 1907– gypsum: Arcadian mine: Houghton: 1898–1908: copper
In the pit was growing a hemlock nearly 400 years old by the number of growth rings. Mining began in 1848, and from 1855 through 1862, the Minesota was the most productive copper mine in the United States. [1] The mine had ten shafts, the deepest of which extended to a depth of 1200 feet (366 m).
The mine was the first Michigan copper mine to switch from fissure mining to amygdaloid mining, when the recently discovered Pewabic amygdaloid lode was found to cross Quincy property in 1856. [9] High-grade fissure veins contained large, pure masses of copper, but the masses could take days or even months to extract, at high cost.
Early mining used open-pit mining methods, but was replaced with underground mining by 1880. [3] The Marquette Iron Range was discovered in 1844 by a party of surveyors led by William A. Burt, who found that their sensitive magnetic compasses produced skewed results because of the concentration of iron in the land they were surveying. [1]
Iron mines of the era exploited the "natural" (soft) iron-rich ores in a 15 kilometer-long stretch in the central portion of the range straddling the Michigan-Wisconsin state line. These mines were mainly of the underground shaft type, which were among the deepest iron mines in the country.
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The Michigan State Geologist Douglass Houghton (later to become mayor of Detroit) reported on the copper deposits in 1841, which quickly began a rush of prospectors. Mining took place along a belt that stretched about 100 miles southwest to northeast through Ontonagon, Houghton, and Keweenaw counties.