OF CORNWALL. u g 
different ftones r. That fpar is fufpended in all waters is likely, but 
in particular waters is evident, from the incruftations formed in 
water-pipes till in time they choak and can tranfmit no more; from 
petrified mofs, and many other phenomena. That fpar is alfo to 
be found in fea-water muft certainly follow, from the fea’s being 
open to and ready to receive all that which fprings will convey into 
it ; from fpars being evaporated by great degrees of heat 8 , and 
therefore capable of being again precipitated by winds and rain \ 
Hence, from the folution I mean of Ipar in common water, come all 
petrifa&ions, and moft of our ftala&ical concretions, marbles, and 
free-ftones, which will ferment with acids, of all which the bafis 
is Ipar ; hence aho the new fparry productions perpetually forming 
and formed in proper nidus’s, by fpar being eafily folved and dif- 
perfed, and as apt to coalelce again into ftone upon the delertion of 
the water in which it is fufpended. However, thefe fparry produc- 
tions are not common with us, and Ipar by itfelf, tranfparent and 
unmixed, is very rarely found in this county. 
Our cryftals are in great plenty and variety : I fhall confider them sect.iii. 
either as plain or figured ; for, even in the plain, there are fome Cornifh cry- 
varieties not unworthy our notice. By plain, (that is quartz ') I ftaL 
mean a mafs of cryftal which covets no particular form, but hardens 
into that figure to which the gravitation of its own parts, and the 
medium in which it forms determines it. Of this fort is that which 
fills the veins and interftices of the ftony Jirata , and the white an- 
gular maffes of fingle-dilperfed ftones common every where in 
Cornwall \ Of this fort alfo are the wavy procefles of cryftal, 
which, like fo many flakes of ice, incruft the perpendicular fides 
of our karns of granites, Plate XIII. Fig. i. Of the plain fort 
are all cryftal horizontal incruftations which coat-over ftones, and 
hang in threads as they defcend, reaching crofs the hollows from 
one tubercle to another '. Of this fort alfo may be reckoned all 
cryftals of the bliftered and mammillary kind, which end in one 
drop, and have their fides preffed into orbicular puftules by the 
[weight of fucceeding drops, as Plate XIII. Fig. u. Of the plain 
kind alfo are all cryftal ftaladtites, of which I have fome fo per- 
fect, which I received from a work, called the Pool, in the 
parifh of Illogan, exhibited Plate XIII. Fig 8 , hi. and iv. that the 
_ f “ Hoc frujiulum & alterum fpati addidi quo- mentioned, in that it is not figured : it is radi- 
niam hccc duo fofftlia [fell. fpatum & quartzum ] fi- cally the fame ftone ; and therefore quartz is cry- 
gun; naturd et efftftu adeo dijimtia anhnadverto hie in fta), plain, not angularly figured ; but yet has 
Anglia nullo modo difcriminccri” If. Lawfon , M. D. fevcral varieties. “ Lapides cryjlalli di£H a quartzo et 
ad auclcrnn^ A. D. 1740. fpato folumfigura differunt.” Lin. Syft. Nat. p. 224. 
E Hill’s FolT. page 156. k See before, page 48. 
h See Woodward’s Cat. vol. I. page 113, 116. 1 Philosophical Tranfa&ions, on the Cornilh 
1 Quartz differs only from cryftal, as before- diamonds, by the author. A. D. 1750. 
formation 
