1885.] Mineralogy and Petrography. 797 
dinate division to the latter being designated Pinitoid. In a col- 
umn to the left are given the atomic ratios of sesquioxyds and 
fixed peroxyds, the silica being variable. The zeolitoids include 
besides the zeolites proper, forestite, prehnite, catapleiite, etc. 
Under the spathoids of this class are placed petalite, all feldspars 
and feldspathides, including iolite and sodalite, the scapolites, 
barylite, milarite, gehlenite, sarcolite, melilite, wohlerite an 
eudialyte. The adamantoids include keilhauite, schorlomite, 
ilvaite, idocrase, garnet, allanite, beryl, euclase, ardennite, axinite, 
epidote, zoisite, jadeite, spodumene, sapphirine, staurolite and the 
various tourmalines. In the phylloids are included the whole of 
the micas from phlogopite and biotite, through seybertite, chlor- 
itoid, lepidolite and margarite to damourite and the muscovites, 
With the phylloids, and near the magnesian micas, come the 
various chlorites, while parallel with the non-magnesian or mus- 
covite micas are placed the pinitoids, including besides pinite, 
or geiseckite, jollyte, fahlunite, bravaisite, cossaite, gimbellite, etc. 
he Persilicates are all gathered in two columns under the 
heads of Kaolinoid and Adamantoid, the received ratios of the 
fixed bases and silica being given in an adjacent column. The 
kaolinoids include the various hydrous silicates of alumina from 
the highly basic schrotterite, through kaolinite and halloysite, to 
to cimolite and smectite. With these are placed chloropal and 
also pyrophyllite. The adamantoid persilicates include besides 
dumortierite, fibrolite, cyanite and bucholzite, andalusite, topaz, 
the zircons and anthosiderite. 
The relations of fluorine in silicates like topaz and chrondro- 
future consideration. 
If we regard the silicates as constituting a natural order, the 
three groups already noticed may be called suborders; A. Proto- 
silicates; B. Protopersilicates; C. Persilicates. The divisions of 
these designated Pectolitoid, Zeolitoid, Spathoid, Adamantoid, 
Phylloid, Ophitoid, etc., will constitute tribes. The tribal char- 
acters of the spathoids and the adamantoids being repeated in the 
-suborders, we have A. and B. Spathoids and A. B. and C. Ada- 
mantoids. The subdivisions of these tribes into families, genera 
and species cannot here be discussed. The genus feldspar, includ- 
ing anorthite, albite and perhaps iolite, with other genera, some 
of which are represented respectively by orthoclase, by leucite, and 
by sodalite, will constitute the family of the feldspathides. The 
families of the micas and the pyroxenides in like manner will each 
include several genera, having different values for V. 
