Prof. T. G. Bonney—Serpentines from the Rhetian Alps, 539 
crossed by the Julier road about 500 yards below the village of 
Rofna (between Tiefenkasten and Molins). The serpentine is a com- 
pact, dark purplish-green rock, of characteristic aspect, showing oc- 
casional small folia resembling an altered bronzite. The rock is 
greatly jointed and crushed, with slickensided surfaces, coated with 
a polished green or waxy-green mineral; so that in part it has 
almost a schistose aspect, and the true structure can only be seen on 
a cross fracture. The serpentine is overlain by a reddish to greenish 
schistose rock. The junction of these is difficult to examine, but the 
relations of the two suggest that the former is intrusive in the latter. 
The following is a description of the microscopic structure of this 
serpentine. 
The slide is traversed by irregularly reticulated strings of clotted 
opacite, obviously following cracks, and deposited on their sides. 
The interspaces exhibit a fibrous border, dull bluish white with cross- 
ing Nicols; the “eyes,” or more granular centres, being often dark 
with crossed Nicols; in short, all the structures characteristic of an 
altered olivine rock. Scattered in this ground-mass are small plates 
of irregular outline, now of a serpentinous character, but still showing 
one close, rather wavy, parallel cleavage, and traces of another, 
much less distinct, and inclined to it at a considerable angle. In 
this mineral we need not hesitate to recognize an altered bronzite, 
or, perhaps, rather enstatite, as it is wholly, or almost wholly, free 
from opacite. Probably much of the opacite in the rest of the 
slide is magnetite, but the grains are not very definite in outline. 
Two or three very dark-brown grains may be picotite or chromite, 
and there is a flake or two of ironglance. There can be no doubt 
this serpentine is an altered olivine-enstatite rock. 
In the lower part of the Val da Faller, which joins the Ober- 
halbstein Rhine at Molins, are four dyke-like masses of serpentine. 
Debris or turf generally just mask the actual junctions, but there 
can be no doubt that they are intrusive in the green schist, as they 
cut (in one case very clearly) across the bedding. The two rocks 
are quite distinct in character. The description given above will 
apply in general terms here,—these serpentines having the same 
shattered slickensided character, so that it is most difficult to obtain 
even tolerable specimens. Fragments from two of the masses have 
been examined microscopically. It is needless to describe them in 
detail. They have undoubtedly been olivine-enstatite rocks, though 
now perhaps a little more altered than the last. The schist, a dis- 
tinetly bedded rock of pale-green colour, compact and slightly earthy 
in aspect, is seen under the microscope to consist of a minute granular 
kaolin-like mineral, interspersed thickly with flakes of a rather 
fibrous, almost colourless mineral (probably uniaxial, and one of 
the chlorite group), with much ferrite and some viridite. A little 
felspar is recognizable in nests. At the first glance it seems dubious 
whether the rock should be classed with the true schists, but closer 
study leads me to the conclusion that, though very minute, the 
constituents are mainly of secondary origin. 
About 450 feet above Molins, the road and river cross another 
