'A SYSTEM O'F 
32 
form. At Schneckenftein in Saxony, thefe 
criftals are found of a prifmadcal od:- 
oedral form, with no points, but fiat, 
' and with fome facets at the top ; however 
without doubt the oriental topazes have ano- 
ther figure 
Experiments by fire have been made on 
the Schneckenflein topazes by Mr. Pott, 
as may be feen in his Lithogeognejia, 
To this kind I refer 
The pale yellow topaz. 
Which is nearly uncoloured, and is found 
at Schneckenflein. 
h. The yellow topaze, from Schneckenflein o 
€. Deep yellow, or gold coloured topaz, or 
oriental topaz* 
d. Orange coloured topaz. 
SECT. XLVL 
E, The yellowifli green topaz, or Chryjolite, 
Is of a grafs green colour, and ma? 
perhaps belong to fome other fpecles, which 
might be difcovered, if it could be ob- 
tained rough, or in its matrix, and large 
* I have got fome rough Brazil topazes, which are prifma- 
tical, and of a rhomboidal quadrangular figure, pointed at 
one end 5 but as thefe feem to be broke oit at the other 
end, it is very likely, that they, as well as many other 
criftals, may be pointed at both ends, when nothing has 
impeded them during their’ crillallifadon. 
Befides thefe, I have got fome 'fragments of other topazes, 
likewife faid to be from the Brazils, which are all of them 
prifmadcal, but plainly Ihew, that fome are pentagonal, and 
. other regular hexagons with points. 
The topazes iofe their colour in the fire, but fome of them 
turn red in a certain degree of heat, and are therefore very 
much ufed inilead of the pale rubies, and even are often- fold 
as fuch. 
enough 
