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XV. On a new Locality of Amblygonite , and on Montebrasite, a new Hydrated Aluminium 
and Lithium Phosphate. By M. A. O. Des Cloizeaux, Member of the Lnstitute of 
France. Communicated by Professor W. H. Miller, Foreign Secretary B.S. 
Received November 27, 1S71, — Read February 20, 1873. 
Until last year the Amblygonite from the neighbourhood of Penig in Saxony had 
alone been analyzed — namely, by Berzelius and by Bammelsberg. The beautiful trans- 
parent or translucent specimens found in 1862 at TIebron, Maine, U.S.A., had been 
merely tentatively examined by Prof. Brush, who announced the presence in them of 
lithia in considerable quantity. Their similarity to the Penig mineral, however, led to 
their being looked on, without further investigation, as Amblygonite. These specimens, 
less rare and more transparent than those from Saxony, had enabled me in 1863 to 
determine their crystalline system and their birefringent optical characters'*. 
In 1870 M. Moissenet, mining engineer, sent me a mineral which had been found in 
considerable quantities in the tin vein of Montebras (Creuse). This mineral, though 
resembling the Amblygonite of Hebron, appeared to me so far to differ from it in its 
optical characters and in the composition, deduced from an imperfect analysis made in 
the laboratory of the Ecole des Mines, as to justify my distinguishing it under the name 
,of Montebrasite f . 
Afterwards, towards the close of 1871, I received from M. Moissenet another 
specimen coming from Montebras, which presented all the characters of the American 
Amblygonite, and which consequently was easily distinguished from the Montebrasite, as 
I showed in my notice read to the Academy on Nov. 27, 1871. 
Subsequently to the publication of this note, the analyses made by Pisani (Comptes 
Bendus des Seances de l’Academie des Sciences, seance du 26 Dec. 1871, tom. Ixxiii. 
p. 1479), by Kobell (Sitzungsberichte der bayerischen Acad, der Wiss., Feb. 3, 1872), 
and by Bammelsberg (Berichte der deutschen Chem. Gesellsch. Berlin, 26 Feb. 1872, 
No. 3, p. 78) proved the identity, in point of chemical composition, of the Montebrasite 
of Montebras and the Amblygonite from near Penig. This identity ought in fact to 
exist in the Saxon variety, for I have lately satisfied myself that a plate cut from a Penig 
specimen, in a direction, as nearly as might be, perpendicular to the two principal 
cleavages, presents the same optical characters as do plates cut from some specimens 
from Montebras, which will be discussed presently. But this is not the case with 
* Comptes Rendus des Se'ances de l’Academie des Sciences, tom. lvii. p. 357. 
t Comptes Rendus des Seances de l’Academie des Sciences. Seances des 31 Juillet et 27 Nov. 1871, tom. 
lssiii. pp. 306 & 1217. 
