A mountain range in northeastern Minnesota, United States. It stretches 180 km from Babbitt in the east to Grand Rapids in the southwest, and is the state's largest iron mining region, including the Vermilion Mountains in the east. The elevation of the entire mountain range is 60-150 m, with the highest point only 610 m. The iron deposits are about 20 km long and 5 km wide from northeast to southwest, and are 60-300 m below the surface. The geology consists of Precambrian chert (quartzite), sandstone, conglomerate, slate, granite, etc., and three gently sloping layers of iron ore are found within these. They are mainly hematite, with magnetite and limonite. In the past, high-quality hematite was mined here, with annual production of over 60 million tons at its peak, but it was all mined out in the 1950s, and today, taconite (iron-bearing chert) with a highly magnetic content of 50-60% Fe is mined here. The main mining towns are Hibbing and Virginia. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
アメリカ合衆国,ミネソタ州北東部の山地。東はバビットから南西のグランドラピッズまで 180kmに及び,東のバーミリオン山地を含むミネソタ州の大鉄鉱山地である。山地全体の標高は 60~150mで,最高点でも 610mにすぎない。鉄鉱床は北東から南西にかけて長さ約 20km,幅 5km,地表下 60~300mにある。地質は先カンブリア時代のチャート(ケイ岩),砂岩,礫岩,粘板岩,花崗岩などからなり,これらの中に 3層の緩傾斜の鉄鉱層がある。赤鉄鉱を主体とし,磁鉄鉱と褐鉄鉱を伴う。かつては良質の赤鉄鉱が採掘され,最盛期には年産 6000万t以上あったが,1950年代に掘りつくされ,今日では品位 50~60%Feの磁性の強いタコナイト鉱(含鉄チャート)が採掘されている。鉱山の中心町はヒビングとバージニアである。
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