| Show 0 FORMATION AND GEOLOGY i the formation and geology of seye troughs constitutes a most interesting study it is not difficult to understand 0 ot comprehend and yet one must examine elamin tho district well before he be Is in any way Q fled to describe it intelligently and CO correctly it is with pleasure then that W wj publish the following description prepared prepare 19 specially for the mining review by david B shea E 11 of II mazuma azuma who has been n n the district for a year or more I 1 the seven troughs mineral belt is essentially senti ally lly a series of intensely folded volcanic i rocks oclis resting on a base of metaphoric slates nd ind granite the structure appears to be a bt auble folding with parallel axis somewhat less than a mile apart the belt s about twelve miles long flanked and par itally bally encircled by the granite on the hyest vest and northwest the double folding na ff nak Z 4 ya 4 AM 0 41 IQ gives rise to fo at least two main mineral bhones i zones coinciding with the north and south trend of the axis of folding the zone of chief ore production to date ate is the most westerly and passes through rough the mazuma hills kindergarten till ill and south through the fairview mine the seven seve n troughs the east zone courses courses through the badger hill and properties artles north and south of that point though the e trend of the formation is northerly and d rutherly gut herly the main channels of erosion fatherly fut ave been cut laterally across the country these lateral valleys are an important feature of the district as they render the west belt assessable asses sible from the main roads of the country and crosscut cross cut the strata to a considerable sid erable depth of the volcanic series intimately associated with the mineralized zones the oldest rock is an andesite of a grayish or greenish to purple color and usually of a streaked or spotted appearance it is usually very much altered in the vicinity of ore veins calcite being a common alteration product overlying the andesite is a rock intimately associated with many of the veins and often forming the ore this is a yellow or white rhyolite this rock is easily distinguished by its well defined flowage lamination on the surface it weathers into thin shaley flakes this rock with some a agglomerates 0 glonie rates and tuffs forms the greater part of the yellow hills so conspicuous in the district it is the foundation of the mazuma hill where along with a dyke of intrusive andesite it forms the walls of the tl i e mazuma lode in the upper levels of the mine the badger hill on the east belt is largely of this rock together with some beds of agglomerate A second rhyolite light red or brown in color occupies a greater part of the belt between the main ore zones and also flanks the mineral belt on either side only an occasional hill shows the remains of almost horizontal upper flows these for the most part are glassy flows sandy agglomerates and tuffs capped with basales ba salts no study was made of them or the kindergarten mill photos by b ifill C higgins the kindergarten tunnel aw X t aim ji ta i oil i k 41 N ar michigan lease on the thor photos by bj vill ifill C higgins george english lease on badger hill their relative position the folding of the strata was accompanied by extensive fissuring assuring and faulting and the intrusion of many dykes these dykes are closely associated with the ore veins in many cases they constitute the vein itself through shearing and replacement of constituent minerals of silica and metallic combinations the most imbor important tant dykes are close grained greeni greenish sli andesite and a black basalt sometimes quartz bearing 1 other d ykes dykes of nature are common it may be said that the veins of the dis brict are intrusive in their nature first because of their being associated with dykes and composed of altered dyke material tc rial and again the and metallic minerals mine als of replacements are of deep seated origin so far the most profitable ores have br bf n lound found in fissures f assures in rhyolite associated with andesite dykes or basalt aciro apiro jo sep pe ul site or at the contact with the basaltic basalt 6 akes and andesite at the north end of the district another class of mines have been opened up these are fissures in an altered granite intrusion 0 or associated with granite and intrusive dykes the veins of the first class are strike fissures and the ores show replacement of crushed and altered ahyo lites the second class of vein is producing some of the best grade of ore i values are about equal in weight of gold and silver but in many cases the gold predominates at a ratio of two to one the free gold is both primary and as a result or the decomposition of an ruby silver ore is in evidence in the lower levels of som some e mines stibnite is sometimes found but not usually with the best ore from the structure and character of the rocks and the origin of the ores of the district it should respond liberally to deep systematic mining there should be no in values or ore shoots while the veins remain in the volcanic rocks |
