It Is Known That The Zechstein Is Situated Between The Muriatiferous Gypsum And The Conglomerate (Ancient Sandstone); Or Where There

Is no muriatiferous gypsum, between the slaty sandstone with roestones (buntesandstein, Wern.), and the conglomerate or ancient sandstone. It contains

Strata of schistous and coppery marl (bituminoce mergel and kupferschiefer) which form an important object in the working of mines at Mansfeld in Saxony, near Riegelsdorf in Hesse, and at Hasel and Prausnitz, in Silesia. In the southern part of Bavaria (Oberbaiern), I saw the alpine limestone, containing these same strata of schistous clay and marl, which, though thinner, whiter, and especially more frequent, characterize the limestone of Jura. Respecting the slates of Blattenberg, in the canton of Glaris which some mineralogists, because of their numerous impressions of fish, have long mistaken for the cupreous slates of Mansfeld, they belong, according to M. von Buch, to a real transition formation. All these geological data tend to prove that strata of marl, more or less mixed with carbon, are to be found in the limestone of Jura, in the alpine limestone, and in the transition schists. The mixture of carbon, sulphuretted iron, and copper, appears to me to augment with the relative antiquity of the formations.) The strata of marl effervesce with acids, though silex and alumina predominate in them: they are strongly impregnated with carbon, and sometimes blacken the hands, like a real vitriolic schistus. The supposed gold mine of Cuchivano, which was the object of our examination, is nothing but an excavation cut into one of those black strata of marl, which contain pyrites in abundance. The excavation is on the right bank of the river Juagua, and must be approached with caution, because the torrent there is more than eight feet deep. The sulphurous pyrites are found, some massive, and others crystallized and disseminated in the rock; their colour, of a very clear golden yellow, does not indicate that they contain copper. They are mixed with fibrous sulphuret of iron,* (* Haarkies.) and nodules of swinestone, or fetid carbonate of lime. The marly stratum crosses the torrent; and, as the water washes out metallic grains, the people imagine, on account of the brilliancy of the pyrites, that the torrent bears down gold. It is reported that, after the great earthquake which took place in 1766, the waters of the Juagua were so charged with gold that "men who came from a great distance, and whose country was unknown," established washing-places on the spot. They disappeared during the night, after having collected a great quantity of gold. It would be needless to show that this is a fable. Pyrites dispersed in quartzose veins, crossing the mica-slate, are often auriferous, no doubt; but no analogous fact leads to the supposition that the sulphuretted iron which is found in the schistose marls of the alpine limestone, contains gold. Some direct experiments, made with acids, during my abode at Caracas, showed that the pyrites of Cuchivano are not auriferous. Our guides were amazed at my incredulity.

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