274 Scientific Intelligence. 
kaolin can be so distinctly followed. (Where fluor-spar predominated 
in the mineral silica might be easily overlooked as when decomposed 
by sulphuric acid, it would be evolved in the form of gas in combina- 
tion with the fluorine. I confess I had neither apparatus nor sufficient 
quantity of the mineral to investigate this point as accurately as it de- 
served, 
massive fluor, in others imbedded in Hematite. 
In connection with the above results, my attention was called to the 
fluor of other localities, particularly that of Zinnwald and Graupen. 
At Zinnwald the cubical crystals of fluor are sometimes altered into a 
substance resembling Speckstein; on analysis this so-called Speck- 
‘silicate of alumina. 
_tregret that it is not in my power to give a series of quantinyes 
more by the cleavage, which cuts through the crystals 
without any reéntering angle or line of interruption. The cleavage af- 
fords in fact regular tetrahed d octah 
as spar; and no one of the faces 
. 
ctahedrons with the same facility 
of cleavage in one crystal was 
