12 Macfarlane on the Primitive Formations 



when again roasted and smelted produces black copper, which, 

 being refined on the small hearth to gahr copper, is sold in Chris- 

 tiania or Hamburg. 



The cobalt mine of Skuterud occurs on a fahlband, which has 

 been traced about five miles, the rock being a quartzose mica 

 schist. Layers of impregnated hornblende and actinolite schists 

 are also of frequent occurrence. The rocks run north and 

 south, and have a dip nearly vertical; sometimes inclined slightly 

 to the east, sometimes to the west. In these rocks the following 

 metallic minerals have been observed ; magnetic, iron and 

 copper pyrites, characterising the fahlband ; cobalt glance, co- 

 baltine, cobaltiferous mispickel, magnetic iron ore, graphite, and 

 molybdenite are found more sparingly, impregnating the fahl- 

 band at certain places. These latter minerals do not occur 

 in veins, but they are sometimes associated with quartz. They 

 seem to form rather a succession of small layers, running parallel 

 with the foliation of the rock. They are by no means generally 

 distributed through the fahlband, and it has only been by taking 

 out the whole mass of this, that the cobaltiferous portions 

 have been jrot at hitherto. The fahlband itself has a breadth 



o 



of from one to five fathoms, and it seems, toward the north, 

 to be divided into two difi"erent bands, separated from each 

 other by a large mass of dead rock. The mines were discovered 

 in lt''72, and have since been uninterruptedly worked, notwith- 

 standing an extraordinary decrease in the value of the products. 

 The treatment of the ores, as at present pursued, is as follows. 

 The rocks are broken and sorted into rich and common 

 ores. In the treatment of the smalls by means of a fall 

 wash-work, washed ore of a very small size is produced, besides 

 the above sorts. The whole of this ore is so finely disseminated, 

 that it can only be advantageously treated by stamping and 

 washing. The stamping mill is of the construction used in 

 Saxony. The resulting stamp meal and slimes are concentrated 

 first on percussion and then on sleeping tables. The rich ore 

 treated in this manner yields per ton 86^ lbs. of fichlich, contain- 

 ing 17.96 lbs. metallic cobalt. The common ore yields per ton 

 29 lbs. of schlich, containing 1.88 lbs. of cobalt. The poorer 

 schlichs are further concentrated by being partly roasted, and 

 smelted with an addition of some limestone and slag. The 

 resulting slag is set aside. The regulus (sulpharseniurets of 

 iron, cobalt and copper,) containing about 22 per cent metallic 



