M I N E R A L O G Y. 
SECT. XLIIL 
4f 
St Red, Ruby, Adamas mher, Rtiltniis. 
Which, by lapidaries and jewellers, 
is, in regard to the colour, divided into, 
I. The Ruby, of a deep red colour^ inclin- 
ing a little to purple. 
2* Spinel!, of a dark colour. 
3. The Balafs, pale red, inclining to violet. 
This is fuppofed to be the mother of 
the rubies. 
4. The Rubicell, reddifli yellow. 
How, ever, all authors do not agree in 
the characters of thefe ilone-s. 
‘^ Thefe gems are rather too precious to be examined by all 
poffible experimental means ; however they are, by reafon of 
their hardnefs, and the particular form of their criftals, with 
more propriety looked upon to be produced from their own 
feparate principle, being cither formed in a fingle drop, or 
criftallifed out of their matrix, rather than to be ranked 
among the quartz crifials , for if the heat of the fun, or the 
climate were the caufe of the hardnefs of the diamond?, why 
is not a quartz criflal on the coak of Barbary harder than ons 
from 'the province of Jemtland in Svv-eden ? and vvho can af- 
fure us heS'e in Europe, if, at the place where the diamonds 
are dug, there is any kind of rock, or nor, which is the bans 
or matrix of thefe precious ftones, in the manner as the quartz 
is of the rock or quartz cridals ? The account which Ta- 
rernier has given us, about the digging of diamoncjs at Gcl- 
eonda, agrees with that of the crillals in Jemrland, viz. rhat 
they lye bedded in clay w^ithin clullers of crillals, and in 
cle^ts.^ Now fuch of our criilals are always the clearell, as 
have never been adherent to the rock, and next to them, 
(uch, as by fome unknown accidents in nature, have been fe- 
parated from their bafis ; but fuch, as are yet fixed to the 
rock, are very feldom ht for any ufe : if thi?, therefore, 
fliould happen to be tile cafe b.kew'ife with the diamonds, it 
is no great wonder, that they do not at the very place take 
any notice of the rock,, and iliil leis, that they do not bring 
any of it to Europe, The cluFters or groupes^of criilai from 
STnneckeiirTeiri in Saxony, wherf^in topazes and rock crifcals 
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