122 
NATURAL HISTORY 
rent. It has this farther peculiarity that its fhoots tend all one way, 
whereas, in other crydal lumps, they point differently according 
to the beds they rife from : the only one of this kind I have yet 
feen. It came from Trevafcus mine, in the parifh of Gwynier. 
Fig. xxix. is an afterifk of the cleared: crydal ; its rays hexago- 
nal, fwelling or gibbous in the middle ; their fides not rectilinear, 
but ridged near the edges, and fomewhat hollow, but not uniformly 
fo, betwixt the ridges. The extremities are entire, ending in one 
fharp point ; and it is very plain that they never had any pyrami- 
dal apices : the rays near the bafe fpread horizontally, but the others 
raile themfelves, gradually making a greater angle till the middle 
and highed make nearly a right angle with the bafe. I have feen 
one more of this kind, but not fo entire as this curious fpecimen * . 
Fig. xxxiv. a triangular pyramid, the fides confiding of triangles 
equal to one another, and to the bafe. 
Fig. xxxv. a triangular cunoeid jointed crydal, the bafe of the 
one alternately contiguous to the apex of the next adjoining. 
Thefe are the principal varieties of crydal which a colledtion of 
fome years from our Cornidi mines has afforded, and I doubt not 
but new didin&ions and different forms, and very likely more elegant 
ipecimens, will occur to gentlemen who will indudrioudy colled:, 
compare, and fet in order, the crydals of different mines. Of this 
the curious Mrs. Grace Percival of Pendarves (to whom this colledion 
is indebted in more than one indance) has offered us a fair pattern, 
by fixing fide by fide in her Fofiillary an infinite number of crydals 
of various and the cleared waters, in all drapes, fingle and in cluders, 
modly out of mines in her own lands, all out of her neighbour- 
hood. So many rich fubjeds will well remunerate the attentive 
infpedion of every inquifitive Fodilid at her feat of Pendarves, in 
the Parifh of Camborn, Plate the XIV. 
sect. v. The figures in Plate XIII. are all of the natural fize, but the 
Their fize. bodies defcribed are not always of the larged kind. The larged 
hexagonal crydal which I have yet feen found in Cornwall, is ten 
inches and a half in girt near the bafe, and foven inches and three eighths 
high. It weighs three pounds and half an ounce. From this fize we 
have thefe crydals of all dimenfions down to that of a fmall pin. 
sect. vi. They are fometimes of a fine clear water, and are therefore 
^andcoiour common ty called Cornifh diamonds, and of all our badard diamonds 
in this nation are edeemed the bed p ; but they are not all colourlefs, 
* The intermediate numbers are explained in the Cornifh are the beft, much better than thofe 
the following pages. on St. Vincent’s rock near Briftol.” Grew’s Muf. 
p “ Of our baftard diamonds here in England R. S. Part III. Chap. iv. 
fome 
