HO NATURAL HISTORY 
pebble of like kind is charged with yellow fpots of a light-ochre 
colour, from the fixth of an inch diameter and under. 
N°. iii. A very blue violet purple grGu?id y granules lighter co- 
loured, thinly difperfed from the eighth of an inch and under in 
diameter, a beautiful ftone from the beach in Mount’s-Bay. 
N°. iv. We have alfo the porphyrites with larger grains, and a 
green ground , which Hone though not of a purple colour, yet, being 
of like confidence and texture, mud be ranged alfo among the 
porphyrites. 
N°. v. Dr. Woodward takes notice of u a done b finely varie- 
“ gated with fpots of red and white, with flakes of white talc in 
“ it, found near Caldock, in Cornwall, called v/ith uc the Worm- 
“ Seed Stone, becaufe thick fet with fmall bodies not unlike the 
“ Semen Santonici, or Worm-Seed, fomewhat related (lays he) to 
“ the porphyry kind.” 
I have yet found thefe porphyries only in nodules ; but fo many 
being to be feen, efpecially after a dorm, on the fea-fliore of Mounts 
Bay, particularly near Pons-an-dane river, in Gulval, it is not un- 
likely that there may be fome veins or fircita of them in the funk 
rocks under the fea, though I have, upon my fearches among the 
rocks at low- water, not difcovered any. The porphyry was thought 
formerly peculiar to Egypt, and much admired for its colour and 
hardnefs. The ancients had a method of working it with tools, 
but that method is as yet unknown to the moderns. It is a clofor- 
grained kind of granite, with its charge or Ipots more neatly placed, 
and more didin&ly finilhed. 
sect.v. It has been generally held, that in Cornwall we have no dalac- 
Md ft afabdf S t ^ es ’ ^ ut Ads ls a midake ; for fome fmall drop-dones or ftalacflites 
in CornwaJ). have been fent to the Royal Society from Pendinas cadle, faid to 
have had a drong fcent ' ; and in the caves of a cliff, near the 
Holy-well, in the parifh of St. Cuthbert, there are feveral dillati- 
tious productions of a fparry kind. Some are gritty, and their grit 
little harder than chalk ; others are more dony, and hang from the 
roof in fangs, like the anemone root, but fometimes in fmall tubu- 
lar dalactites with green and fometimes red efilorefoencies. The 
fame fparry juice forms large bunches of done on the fides of the 
caves, and as it drains through the fand, and blown fragments of 
fhells, fixes both, forming itfelf into thin prominent wavy edges, 
with quadrangular cavities between, making a pretty kind of fret- 
work. On the floor of thefe caves the fame dony juice forms a 
more uniform mafs, fpreading itfelf into a fluor of the alabader 
Cat. vol. I. page 64, d. 36. c Grew’s Muf. R. S. page 320. 
kind 
