and Bucholzite, with Kyanite. 159 
There is also found at Brandywine Spring, Delaware, a mineral 
which has been extensively circulated under the name both of Bu- 
cholzite and Fibrolite. A specimen from this locality furnished me 
the following results, viz., quantity taken, 1:0675 gr. Found— 
Silica, : ‘ 0°386 = 36:159 per cent. 
Alumina, . ‘ 0°679 = 63°525 
1:065 99°684 
This is evidently identical with Kyanite. Minute traces of iron 
and manganese, which are found in both the above, are regarded as 
of no importance in the result, being mere impurities. * 
Fibrolite of Bournon.—This mineral was first distinguished by 
Count Bournon, who detected it among the associated minerals of 
corundum from India and from China. The name has reference to 
its fibrous character. It was analysed by Chevenex, who found— 
Silica, : : ; 38:00 
Alumina, 3 z : 58°25 
96°25 
Even upon so imperfect an analysis, there has been no hesitation 
with most writers in referring it to Kyanite. Having a specimen of 
this mineral from Count Bournon at my disposal, 1 have analysed 
it.t It yielded, on 0°427 gr. taken,— 
Silica, . ; 0:1551 = 36°309 per cent. 
Alumina, . 5 0°2665 = 62415 ... 
Magnesia, . 4 0°0030 = 0-702 
0°4246 99°426 
The results just given leave it no longer possible for us to separate 
Sillimanite, Bucholzite, and Fibrolite, from Kyanite. The hardness 
of Sillimanite proves also to possess the same inequality, on different 
faces, which is found on Kyanite. The cleavage face is much softer 
than the angle or side of the prism, so as to be easily scratched with 
a sharp point of hard steel. The crystalline forms of Sillimanite 
* It may be objected to the conclusion, that Bucholzite is identical with 
Kyanite that I have not analysed a specimen of the original mineral. This I 
should have done could I have procured one in time for my present purpose. 
The Chester mineral here analysed was received by Baron Lederer from Dr 
Nuttall ; and, so far as I can learn, no one questions that the mineral from that 
locality corresponds entirely with the Bucholzite of Brandes. I am convinced 
that those chemists who have obtained so high a per-centage of silica in their 
analyses of disthene minerals, had not taken the precaution to employ the aid of 
caustic potash, added to the assay during fusion, as recommended by Berzelius ; 
and that if they had re-analyzed their silica, they would invariably, in cases 
where the amount exceeded 38 per cent., baye found in it a portion of alumina. 
+ The specimen referred to was taken from the collection of Col. Gibbs (now 
in Yale College), and was received by him from Count Bournon in a large col- 
lection of gems which this gentleman furnished to Col. Gibbs. 
