and Equivalent Volume of some Mineral Species. 217 
a Density. _ | Volume. 
Epsom salt, S7MgzO2s, H19049 1-750 . 
\Chrysoberyl, ((Besoals0)O120 3'800 504: 
Andalusite, (sizoaléo)O100 | 3300 | 497°8 
az (sisoals6)Os0F 3570 , 
Chrysolite, sitsOas(MgasFes)Oas 500 512°8 
Picrosmine, siasO48(Mg24H12)O36 2-680 500:4 
Serpentine, sis6Os6(Mg27His)O4s 2-550 4965 
Villarsite, sissOs6e(Mg33Fe2MnH9)O«5 2-975 4758 
lolite, sia5O45(al27 Mg7Fe2)Os6 2-660 515: 
Aspasiolite, isiasOa5(ala7Mgs-sPeH10.5)O4s4| 2-764 506° 
Scheerer in the paper last cited, has, shown that iolite and as- 
pasiolite not only crystallize alike, but are even associated in the 
same crystal, one species passing into the other, and the iolite or 
cordierite often forming the central portions of the crystal. ‘The 
formation of the hydrous species from an alteration of iolite, re- 
quires an agency which should at once remove magnesia and 
supply water; Scheerer from the characters of the accompanying 
minerals, rejects the idea of such a change, and seems to regard 
the association as an instance of the crystallizing together of two 
Serpentine afforded Scheerer an amount of water corresponding 
to the formula given above, but G. Rose has lately described 
crystals from this locality which have a centre of unaltered 
chrysolite; one of them gave on analysis 53: per cent. of mag- 
nesia and only 4: of. water, corresponding according to him to a 
mixture of the two species. He hence in opposition to Scheerer, 
Tamnau and Bébert who have examined the locality, regards 
these, and indeed all crystals of serpentine and the related species, 
as psendomorphous. pe 
A glance at the formulas given above, will suggest an objection 
to this view. Chrysolite might be converted into picrosmine, by 
removing one-half of the magnesia, and partly replacing it by wa- 
ter, for the silica in equal volumes is the same. But if a conver- 
sion into serpentine is supposed to be effected by adding water, and 
removing a portion of oxyd of iron and magnesia, the 48 siO of an 
equivalent of chrysolite will make one and one-third equivalents 
of serpentine, and the volumes of the two species will be 5128 : 
662-0, or since the volumes of equivalents are theoretically iden- 
tical, as 3:4. But neither in the magnesite and ilmenite which 
enclose the serpentine of Snarum, nor in any localities of erys- 
# Monatsber. Berl. Akad, cited in this Jour., vol. xii, [2] p. 815. 
Sxconp Szrres, Vol. XVI, No. 47.—Sept., 1853. 28 
