Abstract

The Ropes Mine, situated three and one-half miles northwest of Ishpeming, Michigan, was operated from 1883 until 1897 and produced $647,902.37 gold and silver. Recovery of $54,929.38 from some of the old tailings brings the total to $702,831.75.The ore mined occurred in nearly vertical quartz lenses cutting diagonally across a vertical tabular body of Keewatin lavas and volcanic fragmentals separating two bodies of Laurentian peridotite. The Keewatin and immediately adjacent peridotite are strongly sheared, the former being chloritized and the latter serpentinized and steatitized. In the vicinity of the quartz lenses the Keewatin is silicified, sericitized and pyritized. The mineralization is probably of post-Middle Huronian age.The quartz veins carry tetrahedrite, pyrite, chalcopyrite and minor amounts of other sulphides, and the ore milled ran about .2 oz. gold and .9 oz. silver per ton, of which nearly one-third was lost in the tailings.Recent explorations have shown another type of ore occurring as a pyritic dissemination in schist adjacent to the quartz veins. There is about eight times as much ore of this type averaging .13 oz. gold and .7 oz. silver as there was in the quartz vein nuclei.The old mine was over 800 feet deep and recent diamond drilling from the bottom level has shown the persistence of favorable rock alteration and gold values for hundreds of feet below that elevation.

First Page Preview

First page PDF preview
You do not currently have access to this article.