Of Regular Stones. Part III 
In which is alfo immcrfed a fort of fmall Sand-coloui'd 
Stones, fo hard as to fcratch Glafs. The other, hath alfo 
a mixture of fome parts that are Green. The Blew and 
the Green, are both, and they only diilbluble upon the 
effufipn of Acids. I 
(a) Boet. de The beft of thefe Stones are the Bleweft. (a) They have 
Sxaetde tn ' s P ro P ert 73 /<:. to look blew by Day, (b) and Green 
Gem. by Candle-light. Many, faith Boetius, have judged this to 
be reckon'd by Pliny, amongft Jafpers with the Name of 
Boreas. But either Pliny and the Ancients,or thofe that make 
that judgment of them, were greatly miftaken. For this 
is a very foft Stone, and eafily diffoluble, with Ebullition, 
immediately upon the effufion of fome, efpecially Nitrous 
Acids : and may be fcraped with a Knife. So that I am 
of Opinion 5 That 'tis nothing elfe but a fort of JErugo 
in fome meafure petrify cl. Which alfo is further confirmed 
in that it doth not only refemble that in Colour, but, be- 
ing ( as it is eafily ) burnt, is of the fame Taft. So that it 
is no marvail, if this Stone, with Age and efpecially much 
worn and expofed to theAir,loofeth the beauty of its colour. 
And that it may be reftored to the fame by Oil of Vitriol-, 
which eateth off its faded Surface. 
CHAP. V. 
Of REGVLAR STONES. 
AS Gems are diftinguilhed chiefly by their Colours 5 fo 
other Sto?ies Regular, by their external Forms. This 
is of two general kinds. Such as is Circumfcriptive, or 
depending upon the whole Stone, as ex.gr. in the Eagle- 
Stone $ and this is properly call'd the Figure. Or fuch as 
is Accumulative, where there is a repetition of the fame 
Figure in feveral parts, as in Mufcovy-Glafs, compofed of 
parallel Plates : and fo for the reft , whereof in their 
order. 
A GLOBULAR PEBBLE, an inch and I in Diametre, 
whitifh and femiperfpicuous. It feems to be an Allay to- 
wards the Eagle-Stone, hereafter defcribU 
A 
