eee 
J.D. Whitney on Minerals of the Lake Superior region. 19 
In analysis 11, in which all the yeaa a are determined, as 
well as the relative amount of the oxyds of iron, the calculation 
ie for the ratio of the oxygen of water, protoxyd bases and 
e silica, leaving out of consideration the peroxyd of iron as 
belt a mechanical intermixture, the numbers 1:14 
or, almost snes: i 14:2, which is the ratio given os ha 
analyses of serpen 
Stlver.—Native silves still continues to be found in considera- 
be pee te in connection a - mag - A gees a mines 
liff. 
was really found, as the miners are well known rm appropriate 
almost all the silver they discover. The metal has never been 
noticed by me in distinct crystals, except in one instance, namely, 
at the Copper Falls mine, where a few well formed cubes about 
one-tenth of an inch in diameter were obtained. 
Most of the fine specimens of silver from the Lake have been 
associated with calcite, which is dissolved away by an acid, leav- 
ing the metallic mass exhibiting the impressions of the planes of 
this ae as is the case with the copper specimens, as before 
remar. 
Zeolites, —To close this article, a few remarks may be added on 
the occurrence of the zeolitic minerals in the Lake Superior re- 
gion, and especially as meme re 
By far the most abundant zeo per-bearing veins 
are eg and laitamotisite, (0% or ie sete species, leon- 
ha he cases are rare, however, in which either of these 
soniee crag ge the bulk of the gangue of a vein, except 
in the case of narrow strings and bunches of limited extent, 
Quartz andiealoite are the redominating vein-minerals, the zeo- 
lites being decidedly subordinate to these, especially in n the great, 
productive lodes. The zeolites, moreover, are chiefly confined 
to transverse veins, or those crossing the formations at a high 
angle: in the Ontonagon region, where the great lodes have the 
same strike as the beds of rock, zeolitic minerals are of compara- 
tively rare occurrence in mas vein-stone. In this class of veins 
the vein-stone proper. Datholite may be noticed in a few in- 
stances among the transverse veins, as forming the larger portion 
of the gangue near the surface; but in no such case has mining 
been carried to any moneidanene depth, so as to ascertain how 
far this state of things conti 
n the whole, the diminution of the zeolitic portion of the 
vein-stone is marked as the mines are extended downwards: the 
y crystalline mineral observed in a recent careful examination 
