CHAP. VI. 
i 
i 
Of STONES 1RREGVLAR. 
AS GEMS are chiefly diftinguifhed by their Colours, 
and all other Stones Regular, by their Figures : So 
thefe, by the different degrees of Hardnefs. 
EMERY. Smirk. Of a kind of blackilh Iron-colour. 
The hardeft of unfigur d Stones. And is therefore ufed 
for the polifhing and cutting of all Gems, except the Dia- 
mond. For the hollowing of flinty Mortars, together with 
Sand, (a) For the brightening of Armour, and all Metal- Aid 
lick. Equipage. And for Moulds or Forms for the cafting 
of Medals and other Coins. Yet Mt. Boyle (b) hath open 3 W 0 f e ^h 
it with a Corrofive Menflruum fo far,as to make an mfuiion p ' i6 °' 
of Galls therewith to turn blackifh. 
A FLINT of the colour of yellow Amber. It alludeth 
to a Topaz. 
A poliih'd FLINT, not unlike a Calcedony. 
A rough FLINT naturally perforated with feveral large 
Cavities running one into another. It feems to be an aflay 
towards an Eagle-Stone, which is commonly a Flint. 
Flints are of all colours. Some fo clear, that fome Jew- 
elers cut and fell them for Bohemick. Diamonds, (c) They j^ Boet * de 
are alfo ufed for factitious Gems with the mixture of Metals, m ° 
in fufion. For making of Glafs. For Mortars for the 
powdering of the Fragments of Gems. And fometimes added 
to melted Metals, to keep them,as is fuppofed,by the Metal- 
lifts, from fpending. (d) (d) AmbroC 
A BALL of SERPENTINE MARBLE 5 called Ophites, 
from the winding of the Veins. Near four inches in Dia- 
metre. Of the nobleft fort 5 confiding of White, and Red 
or Murrey Veins, in Black. 
ANOTHER MARBLE-BALL, two inches and \ in Dia- 
metre,Veined,and fpoted with Red,Sand-colour,and White. 
A THIRD, Veined and fpoted with Black 3 Sand-colour d, 
and White. 
A Ball of ONYCHINE MARBLE,about the fame big- 
nefs 3 on one fide Sand-colour cl, on the other Grey. That 
which is obfervable is this, That inftead of winding Veins, 
S f 2 it 
