ON THE DETRITAL TIN-ORE OF CORNWALL. 193 
of irregular width, and of small, yet unequal vertical -range 
(Carbonas)* spring from the Jodes; and in one locality unconnected 
metalliferous masses of enormous dimensions are imbedded in the 
granite.t| Throughout the whole tract tin-ore has been the principal 
product,{ but here and there copper-ore has, from time to time, 
abounded ; and several mines have afforded other metallic minerals,§ 
but in much smaller quantities. 
From Balleswidden, in the south-east of Saint Just—where the 
rock is, more or less, sprinkled with tin-ore*—the surface declines 
for some distance, towards the south-west; but, as the slope is 
greater in the middle than at the sides, these soon converge in a 
narrow glen, which from Kelynack trends north-westward to the 
beach at Pornanvon.|| A deposit of detrital (Stream) tin-ore in 
the southern and central parts of this ravineM has long since been 
exhausted ; but at Bosworlas, on the northern margin, a narrow 
strip of virgin tin-ground has afforded employment to successive 
generations of the same family during great part of the present 
century. 
* Henwood, Cornwall Geol: Trans: vy, p. 21; vii, p. 179; Pl.i; Journal 
of the Royal Institution of Cornwall, No. xiii, p. xxvi. Haughton and Scott, 
Mineral Agent’s Handbook, p. 39. 
+ Henwood, Cornwall Geol: Trans: v, p. 24. 
+ Within the boundaries of this district the undermentioned masses of 
Jew’s-house-tin have been obtained ;— 
at Pillianeath, in St. Just....weighing 5lbs. Carne, Cornwall Geol: Trans: 
: ii, p. 293. 
», Bossuliack, in Madron.... Pe — Ls Grice, Ibid, vi, p. 44. 
» Lrereife, .; 5000 ols: Ps on an 
» LTremethick,  ,, good » 388,, Wauitixy, (H. M.), Journal of 
the Royal Institution of Corn- 
wall, No. xiii, p. lxxxviii; 
Coutins, Jbid, p. 83. 
§ Borlase, Natural History, p. 209. Carne, Cornwall Geol: Trans: ii, 
pp. 296-304; vi, p. 48. Boase, /bid, ii, p. 384. Henwood, Jbid, v, pp. 12, 
19; Ibid, viii, p. 444. Penberthy, /bid, vi, p. 106. 
|| Borlase, Natural History, p. 76, Pl. xix, Fig. 4. Carne, Cornwall 
Geol: Trans: ii, p. 343; iii, p. 230. Henwood, Ibid, v, p. 13. 
q. The water used for washing (Dressing) purposes at Balleswidden 
flows down this gorge; and particles of ore which it carries off in suspension, 
are collected and subjected to further treatment here. 
