202 F. A. Genth’s Contributions to Mineralogy. 
New Jersey, New York, Connecticut, Vermont and the other New 
England States, as well as Canada, do not appear to have fur 
nished any unaltered chrysolite. 1 frequently have had an oppor 
tunity to examine the so-called “sand chrome ores” from Mary- 
land and Pennsylvania from almost every locality, but in robs 
single instance have I observed the least indication of cbrysolite 
he only sample in which I found very fine grains or conglom 
erations of minute grains of this mineral of a yellowish olive 
green color, in appearance almost exactly like that from no 
latter result from the alteration of pyroxenic and amphibole 
: ickel- 
y ave 
the same origin and result from the decomposition of chrysolite? 
T do not know a single fact which speaks against this suggest’ 
If we assume the nickeliferous or chromiferous tale slates eo 
ntines to owe their existence to chrysolite, this mineral mus 
the origin of olivine (Lehrbuch der chem. und phys. Geologie, 
1, 676-685. Bonn, 1851,) renders the occurrence of speciine’ 
showing the direct change of it into talc, etc. of great scientific 
interest. After having shown that the olivine in the basaltsa? 
lavas cannot have been eliminated from the constituents 0 | 
molten roeks, but must have pre-existed in its present condition, 
before it was intermixed with them, he remarks: “ The questi?” 
own rocks, or whether it is an exclusively voleanic product, 
_ This is certainly a very important question. The occurrenc? 
in strata belonging probably to the lower Silurian, does not 
‘made the more’ probable since almost all the chrysolites analy2 
‘since Stromeyer, have been shown to contain nickel, and, accord: 
‘ing to Walchner, chrome not less generally disseminated thr0vs' 
grains of this mineral, found in the basalts and lavas, ee 
read 
eae 
