( 16 ) 



On the Eelations of Trap-Rocks with the Ores of Copper and 

 Iron, and the similarity of the Schalstein of Dillenburg, the 

 Blatterstein of the Harz, and the Gabbro of Tuscany. 



(Continued from vol. xlvi., p. 306.) 



I. The Relations of Trap-Rocks with Ores of Copper and Iron. 



This extension of geognostic relations between reposito- 

 ries exclusively cupriferous and the trap rocks, gives some 

 importance to a more detailed examination than we have 

 had occasion to make, of the copper ores and traps of Dillen- 

 burg. We find, indeed, between the veins of this country 

 characterised by copper pyrites and the greenstones, which 

 form the principal features of the accidents and composition 

 of the country, relations different from those we have pointed 

 out in Tuscany, and which add some facts to the relations 

 which, in so many instances, render copper ores subordinate 

 to trap-rocks. 



If we examine the environs of Dillenburg on the geological 

 map of Germany, we will perceive that this country, lying to- 

 wards the northeni border of Nassau, forms an islet in the 

 transition mass remarkable for its peculiar composition. 

 Narrow zones, composed of alternations of slates and lime- 

 stones, supposed to be Devonian, run from the south-west to 

 north-east, following the general direction of the great zone 

 of anthraxiferous limestones, which traverse Belgium and 

 Rhenish Prussia, more to the north. These slates and De- 

 vonian limestones lie above the greywackes and Silurian 

 slates of the mass, interrupted by strongly-developed trap- 

 rocks, arranged in zones following the same direction. A 

 second group of the same rocks, affecting the same disposi- 

 tion, is found a little more to the south from Limburg to 

 Weilburg and Braunfels. 



II. Relations of the Schalstein of Dillenburg, the Blatterstein of 

 the Harz, and the Gahro of Tuscany. 



The trap-rocks of Dillenburg cover a considerable surface 

 (8 to 10 square leagues), without, however, being very conspi- 



