Sixth Supplement to Dana’s Mineralogy. 361 
Arrangement of the Hydrous Silicates. 
As many of the hydrous silicates in the Mineralogy are arranged un 
der the species from which they are supposed to have been derived, a’ nd 
are not included in the section of Hydrous Silicates, the following shia 
fied catalogue of the whole is here introduced. 
The two divisions adopted in the Mineralogy, (1) the magnesian and 
iron series with related species, and (2) the alumina series, are retained, 
The Tale and Pyrophyllite scotia are parallel to one another, one 
Magnesian and the other aluminous; both have species with a soap 
agnesia 
it pyrophyllite has the same oxygen ratio as ca and eac + 
(1:2 or 
1; more than be and in the Chlorite section, it is near that of the Mea 
and Andalusite sections (1:14, to 1:1and1: less than 1). The hydrous 
icaceous species of the Phyllite group is related to the anhydrous micas. 
Again, the Augitine, Garnetine and Apophyllite sections are parallel in 
Tatio between the bases and silica as muscovite, that is 5 : 6 e do not 
= that the relation thus indicated is a true one, although iste it ‘for 
€ present. 
Chrysolite and calamine are related in form; if we take a:6:¢ as the 
axes of chrysolite, then a: 6: 14e will be the axes of calamine. Prehnite 
DIVISION I. 
I, TALC SECTION. 
“og pare Grove. 
Talc (Rensselaerite),  - —* 
Authnasiecia, { Chloropheite, Chlorophanerite, Quincite. 
—— Vor. XXVI, No. 78.—NOV., 1558. 
