1886,] - Mineralogy and Petrography. ~~ 7es 
again built up. Several very remarkable instances of this are 
described. A further development of these processes yields 
rocks in which the fragmental character of their constituents can 
not be detected. These form the group of the granular met- 
amorphics, which are subdivded into amphibolites, metamorphic 
amorphic rocks are subject to serpentinization. Grains of horn- 
blende, augite, feldspar, apatite and guartz can be seen undergoing 
an alteration into serpentine. To account for the peculiar features 
of this widespread metamorphism the author supposes that at the 
time of the disturbances the water which the sandstones and 
granite contained was forced out in a heated condition. It was 
nae OP, 1% Pz and occasionally P = and 6P%. a:b:c= 
1:1.67:092, B=—70°. El 
e€ percentages of sulphur and germanium have not yet 
been accurately determined. A new variety of kobellite is 
mentioned by H. F. and H. A. Keller’ from the mines of the 
lian Mining Co., Leadville, Col. The unaltered mineral is of 
a steel-gray color. It is fine grained, crystalline, with a metallic = 
nna gives a black streak, An analysis of pure material 
: ‘ S Pb Bi Ag Cu undissolved residue 
: 15-23 44.08 33-27 5.66 trace . MPa 
Berichte der Deutschen Chemischen Gesellschaft, xix, No. 3, p- 210. 
ae Jahrb. f. Mineralogie, etc., 1886, 11, p. 67. : 
Tb., p. 79. 
