Identity of Pyrochlore with Microlite. S3 



Art. III. — On the Identity of Pyrochlore with the Microlite of 

 Prof Shepard ; by J. E. Teschemacher, and A. A. Hayes. 



Read before the Chemical Society of Boston, March 14, 1842, and communicated 



for this Journal, 



Feeling confident from a close examination of several crystals 

 of the mineral named Microlite by Prof C. 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 constituents 

 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 on the edges. 



Analysis of the Microlite, by A. A. Hayes. 



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 

 a clove brown color and glassy lustre becomes opake and of a 

 fine canella color, with pearly lustre. In the forceps and expos- 

 ed to the outer 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. XLUI, No. 1.— April-June, 1842. 5 



