148 OEIGIN AND DEVELOPMENT OF OKE-DEPOSITS. 



also its position in the ground. f Viewed in this manner the 

 vast and richly-filled subterranean channels, which by the 

 implements of the miner are transformed into caverns of imposing 

 extent, appear what they are— as thin veins in the ground. 



(c) The Perran iron lode. This great lode is referred to by 

 Borlase, who wrote in 1758, and was briefly noticed by Sir H. 

 Delabeche in 1839,* and by Mr. Henwood in 1843. f Later it 

 has been described in more or less detail by Smyth, | Bryant, § 

 and myself |I 



The Perran lode bears about 35" S. of E., and underlies 

 from 3 to 4 feet in a fathom to'' the south-west; and is altogether 

 in killas except where it crosses an elvan. Its western exposure 

 in the cliff at Gravel Hill, at the northern extremity of Perran 

 Bay, is very wide, consisting of two branches divided by 

 a horse of killas. It consists here principally of somewhat 

 siliceous brown hematite, earthy carbonate of iron with traces 

 of lead, and blende associated with garnet ; and was a few years 

 ago worked rather extensively above the adit level by a long 

 adit and by two shafts from above, besides some extensive surface 

 pits. From here it may be traced inland for a distance of four 

 miles to Deerpark, where it takes a turn — at first directly east, 

 afterwards some degrees N. of East, and so proceeding in a 

 curve for several miles more. It is however of little value so 

 far as is yet known after the first four miles, and the following 

 remarks will relate solely to this portion. 



To the eastward of the Gravel Hill Mine, formerly known 

 as Penhale Iron Mine, is the Halwyn Sett, where also a shaft 

 has proved the lode a good many fathoms down — 20 or more. 

 Next come the rather extensive and irregular open works on the 

 brown hematite and carbonate of iron of the Mount Mine, — then 

 the great open works at Treamble, — after that the extensive and 



f The actual fissure or leader, apart from its metalliferous capels might be 

 represented on the above mentioned scale by a sheet of paper thickly or thinly 

 coated with lead on each side in accordance with the dimensions given above. 



* Eeport on Cornwall, &c., p. 618. 



f Trans. Roy. Geol. Soc. Corn., V, p. 108. 



I Trans. Roy. Geol. Soc. Corn., vii, p. 332 (1858), and x. p. 120 (1882). 

 § Rep. Roy. Corn. Polytech. Soc, 1871, p. 98. 



II Rep. Miners Assoc. 1873. 



