E. &. Dana—Chondrodite from the Tilly-Foster Iron Mine. 97 
Following the view of Rammelsberg (that, in consequence 
of the unavoidable loss in the course of the yar Sieg) the higher 
value of each constituent comes nearest to the truth,) Mr. 
Hawes’s analysis becomes as follows. For wcccaeaion the re- 
sults obtained by vom — for 2d type crystals from Vesuvius 
and from Sweden are a 
CHONDRODITE. HUMITE. 
Brewster, N. Y., Hawes. Sweden, v. Rath. Vesuvius, v. Rath. 
44°10 33°96 34°02 
Magnesia 53°72 53°51 59°23 
errous oxide 7°28 6°83 1°78 
Alumina 0°48 O72 0°99 
Fluorine 4°14 4°24 2°44 
99°72 99°26 98°76 
Silicon 15°91 15°85 15°88 
Magnesium 32°23 32°11 35°54 
on 5°66 5°31 1°38 
Aluminum 0°26 0°38 0°53 
Fluorine 4°14 4°24 2°74 
Oxygen 39°78 39°58 41°54 
97°98 97°47 97°61 
Transforming the iron into an equivalent of ap erate, as also 
the alumina (2Al=8Mg), Mr. Hawes obtains further 
Silicon 15:91, Magnesium 35-00, Fluorine 4°14, ae 39°78. 
From these values a formula is deduced, which is essentially 
that of the Swedish mineral according to v. Rath, 
20(Mg ,Si,O,)+Mg,Si, Fl, ,. 
It would have been extremely interesting to have added 
analyses also of crystals of the ist and.3d types; but, as will be 
apparent from what follows, the material was not to be 0 btained. 
A cleavage such as exists in humite ‘(fatale to the basal plane), 
and has been observed by Kokscharow on chondrodite from 
peat could in no case be discovered. The fniotare i is always 
conchoid 
2. Description of Crystals of Type ILI. 
The crystals of the 8d type are exceedingly rare, three or four 
= Sian being all that have thus far been found, and from 
ese only two individual crystals eal be obtained which 
Am. Jour. Sor.—' ee L. X, No. 56.—Aveust, 1875. 
