History of Vernon County, Wisconsin. Together with sketches of its towns and villages, educational, civil, military and political history; portraits of prominent persons, and biographies of representative citizens.

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HISTORY OF VERNON COUNTY.
to pay for its extraction. The Wisconsin gale¬ nas, however, are unusually free from silver, of which they contain only the merest trace.
The zinc ores are of two kinds, the most abundant being the ferruginous sulphide, or the "black-jack" of the miners. The pure sul¬ phide, sphalerite, contains sixty-seven per cent, of zinc, but the iron bearing variety, known mineralogically as marmatite, generally con¬ tains ten per cent, or more of iron. A ferrugi¬ nous variety of the carbonate, smithsonite, also occurs in abundance, and is known to the miners as "dry-bone," the name being suggested by the peculiar structure of the ore.
Both lead and zinc ores occur in limited de¬ posits in a series of limestone beds belonging to the Lower Silurian series. The lead region is underlaid by a nearly horizontal series of strata, with an aggregate thickness of 2,000 feet, which lie upon an irregular surface of ancient crystal¬ line rocks (gneiss, granite, etc.).
The lead and zinc ores are entirely confined to the galena, blue and buff limestones, an ag¬ gregate vertical thickness of some 350 to 375 feet. The upper and lower strata of the series are entirely barren. Zinc and lead ores are found in the same kind of deposits, and often together; by far the larger part of the zinc ores, however, come from the blue and buff limestones and the lowest layers of the galena, whilst the lead ores, though obtained throughout the whole thickness of the mining ground, are especially abundant in the middle and upper layers of the galena beds.
The ore deposits are of two general kinds, which may be distinguished as vertical crevices and flat crevices, the former being much the most common. The simplest form of the verti- cle crevice is a narrow crack in the rock, hav¬ ing a width of a few inches, an extension later¬ ally from a few yards to several hundred feet, and a verticle height of twenty to forty feet, thinning out to nothing in all directions, and filled from side to side, with highly crystalline.
brilliant, large-surfaced galena, which has no accompanying metallic mineral or gangue mat¬ ter. Occasionally the vertical extension exceeds a hundred feet, and sometimes a number of these sheets are close together and can be mined as one. Much more commonly the vertical crevice shows irregular expansions, which are some¬ times large caves or openings in certain layers, the crevice between retaining its normal charac¬ ter, while in other cases the expansion affects the whole crevice, occasionally widening it throughout into one large opening. These openings are rarely entirely filled, and common¬ ly contain a loose, disintegrated rock, in which the galena lies loose in large masses, though often adhering to the sides of the cavity in large stalactites, or in cubical crystals. The vertical crevices show a very distinct arrange¬ ment parallel with one another, there being two systems, which roughly trend east and west and north and south. The east and west crevices are far the most abundant and most productive of ore. The vertical crevices are confined near¬ ly altogether to the upper and middle portions of the galena, and are not productive of zinc ores. They are evidently merely the parallel joint cracks which affect every great rock for¬ mation, filled by chemical action with the lead ore. The crevices with openings have evident¬ ly been enlarged by the solvent power of at¬ mospheric water carrying carbonic acid, and from the way in which the ore occurs loose in the cavities, it is evident that this solving action has often been subsequent to the first deposition of lead ore in the crevice.
The "fiat crevices," "flat sheets" and "flat openings," are analogous to the deposits just described, but have, as indicated by the names, a horizontal position being characteristic of cer¬ tain layers which have evidently been more susceptible to chemical action than others, the dissolving waters having, moreover, been di¬ rected along them by less pervious layers above and below. The flat openings differ from the ver¬ tical crevices also in having associated with the