334 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and joints of separation, it is not applicable to the purposes of 

 building. Between the rivulet and the Tigris, or to the north of 

 the main portion of the town, the serpentine does not rise high 

 above the level of the valley, but, at a few feet above it, is capped 

 by slates and marls, partly crumbling and partly jaspery; the 

 former being of a dark grey colour, and the latter having a 

 brownish red tint. 



The steep south side of the ravine is of a different character. 

 In contact with the serpentine appears a ferruginous breccia, con- 

 sisting of angular fragments of ochreous marls and sandstone, and, 

 more rarely, pieces of porphyry, cemented together by hydrous 

 oxide of iron, and forming a bed of considerable thickness. This 

 is used as a building material, being easily worked, and tolerably 

 durable, but its dull rusty appearance, combined with the total 

 absence of herbage and the strangely coloured sterile slopes of the 

 surrounding mountains, give the place a character of unequalled 

 dreariness. 



Higher on the mountain there rise up, from beneath beds of 

 marl, rugged masses of diallage rock, and these extend in the form 

 of a powerful dyke over the shoulder of the height towards the 

 south. In the portions where it is friable this dyke is deeply fur- 

 rowed by the rains and the tracks of the animals, which are con- 

 stantly passing and repassing with charcoal for the furnaces. Its 

 position in this form and at this elevation is important, as tending 

 to prove that the limestone was not deposited upon it, as might 

 have been argued, from seeing the diallage rock constantly laid 

 bare in the deep valleys, where the superincumbent limestones 

 and marls have been removed. On the summit of the mountain, 

 to the west of the town, marls and limestone are again found ; and 

 the limestone incloses numerous nodules of serpentine projecting 

 from the weathered face of the rock, and thus exhibiting a greater 

 degree of hardness. 



It is to its copper mines that Arghaneh Maden owes all its im- 

 portance. The breccia before mentioned appears to constitute the 

 outer wall of the cupriferous mass. This mass, though it con- 

 tinues in depth to the level of the waters of the Tigris, has not 

 hitherto been opened anywhere except on the surface of the 

 mountain above the town. 



It appears to be but one huge lump of ore, consisting of the 

 double sulphurets of copper and iron, planted amid the serpentine, 

 or perhaps between it -and the marls. In the mines which I 

 entered, not the slightest character of a vein or bed was to be seen, 

 but floor, and roof, and walls consisted entirely of solid pyrites, 

 diversified only by stalactitic coatings of blue and green vitriol. 

 This extended to a depth of 10 or 12 fathoms ; but the additional 

 20 or 30 feet which had been excavated, were filled with water, 

 which had for upwards of a year kept the works almost at a stand- 

 still. It is only by waiting patiently until the month of July or 

 August, that access is gained to the lower parts of the mine. The 

 accumulated rains of the winter and spring at that time gradually 



