the Corundum Stone , and its Varieties , &c. 323 
such an accurate description of its characters as may serve 
to ascertain its real nature. 
It remains for me to speak of the corundum I formerly 
found, or at least thought I found, in Forez, in the mountainous 
parts of that province which are near Montbrison. I find, by 
the Mineralogy of the Abbe Hauy, (Vol. IV. p. 362.) that the 
substance I had considered as corundum, is now looked upon 
in France to be of a different nature. That learned mineralo- 
gist, in the abovementioned work, seems inclined to consider 
it as a species of felspar, and gives it the name of apyrous 
felspar. He admits however, at the same time, that it scratches 
quartz; that its specific gravity is 3165 ; and that it is infusible 
by means of the blowpipe. All these characters seem to place 
it at a considerable distance from felspar. 
The total loss of a very considerable collection of minerals, 
intended expressly for the purposes of study, (and which I 
regret the more from its having been entirely formed, and most 
of the specimens collected in their native places, by my own 
hands, ) leaving me no objects of comparison, I can only consult, 
with regard to the above substance, the few notes I have been so 
fortunate as to preserve, assisting them with such circumstances 
as my memory has been able to retain. 
I find in my notes. 
First, That this substance was inclosed in a yellowish felspar, 
which formed a small vein in a granite rock; that, in some 
parts of the felspar, it appeared in the form of small spots, 
easily distinguishable by their colour, which was red with a 
purplish tinge ; and that, in other parts, it was in masses of 
a rather larger size, from which I was able to extract some 
fragments. 
