< 
X1x 
oppositely, but frequently interlace whilst intersecting the vein- 
stones.* Portions of many lodes—from enclosing bodies identical 
in character with the rocks immediately adjoiming them—have a 
brecciated appearance. These are not uncommon in granite and 
elvan ; but they are more conspicuous in the slate, and especially - 
in the fossiliferous strata of East Cornwall. In some instances 
they form short vein-like bodies, in other they occur as angular 
masses ; occasionally they are sharply defined, whilst, frequently, 
they seem connected by almost imperceptible transitions with the 
ingredients which surround them. Here and there they are en- 
veloped in successive accretions of quartz, each distinguished. by 
some peculiarity of structure or hue; and small cavities studded 
with minute botryoidal concretions of agatine structure sprinkled 
with various crystals occur at intervals between them. When 
they consist of slaty matter the planes of their cleavage often— 
though not always—coincide with those of the neighbouring 
rock ; but where they are composed of granite or elvan their re- 
semblance to the other vein-stones is so close that their relations 
cannot be so well ascertained.t Between these—of which many 
are of scarcely more than microscopic dimensions,—and the masses 
(horses) which—widening from mere lines to many feet or even 
fathoms, and frequently attainmg great length and depth—may 
be said rather to split, than to be contained in, the lodes,t it is 
difficult, if not impossible to draw a distinction§ ; in all, however, 
the mineral characters are identical with those of the immediately 
contiguous rocks. Moreover, when such phenomena occur at the 
contact of different rocks,|| the planes of their junctions in the en- 
closed (horses) exactly confront their counterparts in the (Country) 
sides (walls) of the branches of lodes by which they are enclosed. 
In almost every part of Cornwall certain Jodes contain at intervals 
* Henwood, Edin: New Phil: Journal, xxii., p. 161; Cornwall Geol: 
Trans: v., pp. 53, 172, 181-182. 
+ Carne, Phil: Trans: xevii., p. 294; Cornwall Geol: Trans: ii., pp. 
61,94. Phillips, (W.), Geol: Trans: ii., p. 128. Rule, Cornwall Geol: Trans: 
i., p. 225. Boase, Ibid, iv., pp. 283, 287, 291. Taylor, (J.), Reports of the 
British Association, iil., p. 20. Fox, Reports of the Royal Corn: Pol: So- 
ciety, iv., p. 84. Dela Beche, Report, pp. 322-325. Henwood, Cornwall 
Geol: Trans: v., pp. 210-212; vili., pp. 712-714. Salmon, Quarterly Journal 
of the Geological Society, xvii., p. 519. 
t Pryce, Mineral: Cornub: p. 96. Phillips, (W.), Geol: Trans: ii., p. 
128. Boase, Cornwall Geol: Trans: iv., p. 441; Primary Geology, p. 179. 
Fox, Reports of the Royal Corn: Pol: Society, iv., p. 108. Henwood, Edin: 
New Phil: Journal, xxii., p. 155; Cornwall Geol: Trans: v., pp. 176, 188; 
Vilil., p. 712. Von Cotta, Ore-Deposits, p. 412. 
§ Henwood, Cornwall Geol: Trans: v., p. 211. 
|| Sedgwick, Trans: Cambridge. Phil: Society, i., p. 122. Henwood, 
Cornwall Geol: Trans: v., p. 189. 
B 2 
