294 Geological Society : — 



the lodes reaching 50 feet, and the width of the mineral field half 

 a mile. The underlie is small. The principal lode (the northern) 

 has heen opened on by eight pits, whence have been taken, from a 

 depth nowhere exceeding 32 fathoms, upwards of 10,000 tons of 

 'rich copper-ore. Ore was seen at the bottom at one shaft, the lode 

 being 35 feet wide, including about 5 feet of barren ground and some 

 underlie on the foot wall. 



2. Si/kesville Copper Lodes near Baltimore, U.S. — The country here 

 consists of metamorphic rock ranging N.N.E. and S.S.W., and 

 dipping E.S.E. at a high angle. There are in the lodes granites, 

 gneiss, and mica-slate, with magnesian rocks. The lodes are nearly 

 vertical, ranging parallel to the " country", but dipping in the oppo- 

 site direction. The veins at the top contain much magnetic oxide of 

 iron, but below ten fathoms this changes to pyrites, succeeded and 

 accompanied by copper pyrites. The lode did not appear settled at the 

 depth reached by the existing shafts. There were several points at 

 which pits had been sunk and some copper ore obtained : in aU of 

 them the gossan had a tendency to pass into magnetic iron-ore. A 

 remarkable and very large group of lodes was observed at the " Point 

 of Rocks," where the outcrop is hydrated oxide of iron, worked as an 

 iron- ore to some extent. 



3. Ducktown Copper Lodes in East Tennessee, U.S. — In the south- 

 eastern corner of Tennessee, near North Carolina and Georgia, are a 

 number of lodes, strongly indicated by a rich gossan, and yielding a 

 peculiar and rich black ore which has attracted much attention from 

 American geologists. The " country" consists of altered Silurian 

 schists, alternating with grits ; all striking parallel to the mountain 

 range (N. 30° E., S. 30° W.), and dipping S.E. at a high angle. The 

 talcose schists pass into garnet schists and become steatitic. They 

 are accompanied by numerous strings of quartz, not true veins, the 

 width of which varies from a few inches to 10 or IS feet, and which 

 occasionally show a gossan, either of hydrous or magnetic oxide of 

 iron, with spongy quartz. These veins are nearly parallel to the 

 strike of the country and dip S.E. 



Besides the quartz strings, and within a small tract of six square 

 miles intersected by them, are four gossan beds, of large size but with 

 well-defined limits, which are connected by quartz strings, as well 

 as accompanied by solid ribs of quartz on the foot or hanging wall. 

 These also dip S.E. The enclosing rocks are talcose and steatitic, 

 and contain cyanite, epidote, and garnets. 



The length of the gossan lodes varies from 600 yards to upwards 

 of a mile, the breadth varying from a few yards up to 250 feet ; 

 these dimensions have been proved to be correct by measuring the 

 outcrop of the gossan. Wherever the gossans have been sunk 

 through, masses of black ore, highly cupriferous, have been found 

 at a small depth (from 6 to 90 feet). Below the black ore is a hard 

 dense quartzose veinstone spotted with copjjer ore, which has been 

 worked to the depth of 18 fathoms in some places, but hitherto with 

 no satisfactory result, although fair indications of copper lodes of 

 . the ordinary kind have been found. The thickness of the black ore 



