ORIGIN AND DEVELOPMEN'T OF ORE-DEPOSITS. 1 19 



irregular works at Great Eetallack — followed by the Duchy 

 Peru Mine with its several shafts — and still further east by the 

 trial pits at Deerpark and Penhallow Moor. 



Each of the great Treamble excavations is crossed by a 

 very promising lode of "silver lead," — the lodes No. 1 and 2 

 of the Grreat Eetallack Mine adjoining to the north and east. 

 Nothing has been done to develop these lodes for many years, 

 but in working the iron ore of the outcrop some 60 or 70 tons of 

 lead ore were obtained which contained from 15 to 30 ounces 

 of silver per ton as sold without dressing. The iron lode in 

 the lower or western quarry was in 1873 proved to a depth of 

 17 fathoms by an underlie shaft, and found to improve in quality 

 as it went down. In the upper quarry the lode splits into 

 several branches, the largest going away to the north of east 

 towards the old workings in Great Eetallack, the others pro- 

 ceeding south of east to Berriman's shaft, which was also sunk 

 to a depth of 17 fathoms. Somewhat later other shafts were 

 commenced in each of the quarries, also a vertical shaft at a 

 point between the quarries, but about 40 fathoms to the 

 southward; but this intended "main shaft" was, I believe, 

 abandoned before it reached the lode. 



A little west of the No. 1 lead lode just mentioned is a 

 deposit of unctuous black flucan — much resembling graphite — 

 which in 1873 I found to contain from 3 to 5 per cent, of free 

 carbon. 



At Great Eetallack the lode is several fathoms wide, yielding- 

 near the surface brown hematite and blende, the blende 

 increasing on the whole in depth ; in some months 500 tons of 

 blende have been raised and sold, and the total output must have 

 been many thousands of tons. Many concretionary masses of iron 

 ore were found, some hollow and full of water. (Some lead ore, 

 very rich in silver, has also been raised from this mine at the 

 intersection of the Peru lode, and spots of copper have been seen 

 at times.* In 1860-61, large quantities of blende were raised 

 and sold, but at ver^y low prices, from October to June in the 

 latter year the sales where nearlv 5,000 tons. Considerable 

 quantities were raised for the next few years, and the shaft was 



*Mining Journal. The Perranzabuloe districts, July 27, 1861. 



