XXV 
to the contour and bedding of the neighbouring granite* and to 
the inclination of the cleavage-planes in the adjacent slates.+ In 
each of our several mining districts the lodes are productive on 
similar lines taken at right-angles to their respective directions ; 
hence the phrase “ore against ore;”{ but as the directions of - 
the lodes vary in different districts, the directions of these pro- 
ductive lines are not always the same.§ odes and branches are 
often rich at their junctions; particularly if they interfere— 
whether horizontally or vertically—at acute angles.|| And where 
joints in the rock unite with them on the line of their dip they 
are sometimes productive. ‘The separation of veins and joints— 
on the contrary—tends to poverty. odes of soft or granular 
character, on encountering rocks of more than ordinary hardness, 
split into branches ;4| or 1t may be said—with perhaps equal accu- 
racy—that the entire body, as well of lode as of (country) rock as- 
sumes, for some distance, a veined structure. On the other hand, 
similar appearances sometimes attend the passage of lodes through 
unusually soft strata.** Generally speaking, however, hardish 
rocks are more congenial to tin, than to copper, lodes.tt Both in 
granite and in elvan a well-defined porphyritic structure is a most 
unpromising character ;{{ whilst a gradual blending of the in- 
cluded crystals with the basis is, in both rocks, considered an en- 
couraging circumstance.§§ ‘Transverse joints appear to exercise an 
* Carne, Cornwall Geol: Trans: ii., p. 94. Boase, [bid, iv., pp. 350, 
366. Henwood, Edin: New Phil: Journal, xxii., p. 158; Cornwall Geol: 
Trans: v., pp. 45, 194; vili., p. 672. De la Beche, Report, p. 336. 
+ Fox, Reports of the Royal Corn: Pol: Society, iv., p. 95. De la 
Beche, Report, p. 336. 
: * Carne, Cornwall Geol: Trans: iii., p. 78. Henwood, Edin: New Phil: 
Journal, xxil., p. 157; Cornwall Geol: Trans: v., pp 215-219. Fox, Reporis 
of the Royal Corn: Pol: Society, iv., p. 88. 
§ Henwood, Cornwall Geol: Trans: v., pp. 215-234. 
|| Pryce, Mineral: Cornub: p. 103. Phillips, (W.), Geol: Trans: ii., 
p. 115. Carne, Cornwall Geol: Trans: ii., p. 100. Fox, Reports of the 
Royal Corn: Pol: Society, iv., p. 87. Burr, Mining Review, iii., p. 176. 
De la Beche, Report, p. 233. Henwood, Cornwall Geol: Trans: v., p. 233. 
Von Cotta, Ore- Deposits, p. 420. 
q Pryce, Mineral: Cornub: p. 104. Thomas, (R.), Report, p. 17. Dela 
Beche, Report, pp. 331-332. Henwood, Cornwall Geol: Trans: v., p. 212, 
221; viil., p. 677. Von Cotta, Ore-Deposits, p. 419. 
** Henwood, Cornwall Geol: Trans: v., p. 2138. 
tt Pryce, Mineral: Cornub: p. 95. Fox, Reports of the Royal Corn: 
Pol: Society, iv., p. 117. De la Beche, Report, p. 836. Henwood, Cornwall 
Geol: Trans: v., pp. 226-229. - 
The harder are much richer than the softer portions of the great auri- 
ferous deposit at Morro Velho in Brazil. Ibid, viii., pp. 199-206, Tables 
Vii., xxii. 
t{ Ibid, v., p. 225. Thomas, (C.), Geology of Cornwall and Devon, p. 16. 
§§ Henwood, Cornwall Geol: Trans: v., p. 225; vili., p. 663. 
