, 96 C. U. Shepard, Sr.—Mineralogical Contributions. 
precipitate. From the foregoing results, it would seem little 
—— remains that microlite is a tantalate rather than a colum- 
bate 
5. Redondite. 
I have examined still farther be ro phosphate of 
alumina and iron described by m a previous number of 
this Journal beck xlvii, p. 838), as oconting so abundantly in 
the island of Redonda, W. I, and am now of the opinion that 
it constitutes a species distinct from Gemnit from which it 
differs in several particulars, and essentially in specific gravity. 
Barrandite has gr.=2°576. Redondite gives gr.=2°019, which 
may be presumed to be a little too high, as the three examples 
used in ic a were found on a aes to give 88 
407192 p.c. But as the silica a ‘8 p. c.) was obviously acci- 
dental, the aes of ee Tred acid in the ee mineral 
e water is 24°73 p. ¢ 
6. Piper acid in the Diaspore of Chester, Mass. 
Heermann having found phosphoric acid in the diaspores of 
several 1 eines I thought it worth while to analyze a good 
crystal of this mineral from Chester. It was semi-transparent 
and of a rich hair-brown color with a faint tinge of violet. 
Sp. gr.=3'343. The phosphoric acid was determined by the 
molybdate of ammonia. I obtained 
Wat qe Sak BO 
Phonkaie acid, - 0°32 
Protoxyds iron, with traces of manganese___. 0°38 
0° 
Alumina not determined ; but by difference _- _83°50 
100°00 
7. The Pelham Vermiculite ? 
It occurred to me as — interesting to ened a 
chemical examination of this rather curious exfoliatin 
described by Mr. Adams in a late number of this joni ak 
xlix, p. It is very abundant, and to the eye apparently 
as homogeneous as other softened micas. 
It loses on an average 7 p. c. of water by ignition. By diges- 
tion in hot aqua oe half its weight comes} into solution, 
leaving behind 50 p. c. of minute, colorless ‘scales, closely 
resembling margaric acid. They are so remarkable for their 
haesy of size, freedom from color, and pearly luster, as 
suggest their inorganic composition, Under the 
icpe, however, they very nearly give the distinct lateral 
' 
