Identity of Pyrochlore with Microlite. 33 
Arr. III.—On the Identity of Pyrochlore with the Microlite of 
Prof. Shepard ; by J. E. 'Tescurmacner, and A. A. Hayes. 
Read before the Chemical Society of Boston, March 14, 1842, and communicated 
Sr for this Journal, 
_ Feeuine confident from a close examination of several crystals 
of the mineral named Microlite by Prof. ©. U. Shepard, which I 
obtained from Chesterfield, Mass., the locality mentioned by him, 
that it was identical with the Pyrochlore discovered by Otto von 
Tauk, examined and named by Berzelius, and found in several 
European localities, I handed to Mr. A. A. Hayes about one and 
a half grains of selected crystals, which at the request of this So- 
ciety he kindly undertook to analyze. 
Below is the result of ‘his analysis, as also that of Pyrochlore 
by Wohler; it will be seen fully to confirm my conjecture. I 
have therefore merely to add, that I found crystals varying in 
color from transparent straw-yellow to brick-red and dark black, 
as might be expected in a mineral, several of whose coustituents 
are probably mechanical mixtures ; the transparent and smaller 
crystals, being beautifully modified, as described by Shepard, on 
the solid angles and on the edges of the octahedron. The largest 
crystal I found was that exhibited at the last meeting of this 
Society, and which if extracted from the green tourmaline in 
Which it is imbedded would probably weigh three grains; it has 
modifications s on the edges. PANELS | 42 BSCS SO CEO ALM 
te 
mahi a GAL 
"nay of. the Micali, by A. Acdigig 
Pyrognostic characters.—The surfaces of the fractured crystals 
of this mineral, present an inequality of texture, indicating a 
mixed composition. ‘The colors are also irregularly distributed, 
and vary from light yellow.to clove brown.. When heated in a 
tube, a small quantity of aqueous vapor appears, having an em- 
pyreumatic odor; as the vapor escapes, a translucent fragment of 
aclove brown color and glassy lustre becomes opake and of a 
fine canella color, with pearly lustre. In the forceps and eXxpos~* 
ed to the onter flame of the lamp, the edges of a fragment fuse 
into a canella colored enamel, which in the reducing flame be- 
comes darker, and finally of a clove color. The outer flame re- 
Vol. xzu1, No. 1.—April-June, 1842. 5 
