The iditarod-Ruby region, Alaska

9781130476750: The iditarod-Ruby region, Alaska

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ...least $300,000. Besides the old surface workings, a tunnel has been opened on the veins near the top of the hill, at an elevation of about 4,400 feet. A second tunnel is being started about a quarter of a mile to the southeast, 400 feet lower. The country rock is entirely amphibolite, but a belt of serpentine lies between the Irelan and Plumbago mines. There are two veins here. The eastern vein strikes N. 60 W. and dips 50-60 NE., and the western one strikes about N. 50 W. and has an average dip of 45 NE. The intersection has not yet been developed. The eastern vein has been followed about 600 feet. It pinches and swells greatly, varying from a 1-foot band of gouge and altered country rock to 6 feet of quartz. Very little mariposite was seen, and this only in close association with the country rock. Most of the quartz is banded, and bands of white quartz averaging about 3 inches in width are separated by thin dark bands which consist of altered country rock and crushed arsenopyrite. Dark transparent cryptocrystalline quartz also occurs in places in these darker bands. The quartz is vuggy and the projecting crystals of the vugs are in places coated with successive layers of minutely crystalline and chalcedonic secondary quartz. The ore shoots appear to pitch to the southeast and are said to be more regular than in the other mines of the district, though not of such exceptionally high grade. The rich ore consists of goldbearing arsenopyrite. Free gold is only rarely visible, but when a-polished section of the arsenopyrite is examined under the microscope it is seen to be flecked with minute specks of gold. The arsenopyrite occurs in shoots in the wider portions of the veins, either in fairly definite parallel bands in the quartz or in crystalline bunches. The...

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