REVIEWS 723 



which inclose them and where deposited by solutions from magmatic 

 sources and later enriched through the agency of descending solutions. 



The copper ores occur in three positions: First, in the highly bitu- 

 minous and pyritic beds of the copper shale (Kupferschiefer) ; second, ia 

 the immediately underlying Zechstein conglomerate and the Weisslieg- 

 ende — the latter forming the upper, bleached portion of the Rotliegende; 

 third, in "rucken" or veins cutting any or all of these Permian sediments. 



The dominant metallic minerals in all three situations are chal- 

 copyrite, bornite, and chalcocite. Minor components are pyrite, ga- 

 lena, niccolite, safHorite (C0AS2), and some others. In the copper shale 

 the ore is mainly the so-called "Speise," a fine dust of sandlike ore par- 

 ticles in the rock. Strings and thin plates of sulphides also occur usu- 

 ally parallel to the bedding but elsewhere cutting it at small angles or 

 uniting to form networks of sulphides. Bean and kidney-shaped masses 

 of sulphides also occur. The microscope shows clearly that these sul- 

 phides have developed by replacement of the shales. Nowhere are the 

 sulphide masses rounded as might be expected if they were original 

 components of a mechanical sediment. In the Zechstein conglomerate 

 and Weissliegende the ore minerals characteristically form "sand ore" 

 1-3 cm. thick immediately beneath the copper shale. In the sand-ore 

 spaces between the sand grains are occupied by chalcopyrite and more 

 rarely bornite and chalcocite. Heavy impregnations grade into mere 

 sprinklings of sulphides. In more clayey beds segregations and plate- 

 like masses of sulphides occur. The "rucken" or veins occupy faults of 

 a few centimeters to 100 meters displacement cutting the sediments. 

 Many of them are richly mineralized while others are lean or barren. 

 The maximum mineralization of the veins is in the vicinity of the copper 

 shale and frequently the ore is confined to that part of the vein between 

 the displaced portions of the copper shale. Two generations of ore 

 minerals are recognizable in the veins, the older generation with nickel 

 and cobalt arsenides, calcite, molybdenite, and rarely pitchblende, and 

 the younger generation with copper sulphides and barite. 



If it is assumed that the ores in the copper shale and Zechstein were 

 deposited on the sea bottom at the time these sediments were laid down, 

 it is necessary to assume that copper-bearing solutions were contributed 

 to the sea by streams from the land or by submarine springs. The land 

 areas of that period contained no rocks which by weathering or other- 

 wise can be supposed to have yielded copper-rich solutions. If sub- 

 marine springs had been the source of copper-bearing solutions the ores 



