1893.] ; Mineralogy and Petrography. 565 
the surrounding rocks the granite becomes gneissic, and everywhere it 
is cut by dykes of aplites, porphyries and lamprophyres. Where the 
aptites penetrate the gneisses they possess the usual characteristics of 
these rocks, but where they pass from the schists into the granite they 
become porphyritic, showing a fine grained groundmass of quartz, 
orthoclase and mica and numerous phenocrysts of the same minerals 
and garnet. Like the granite the aplite components exhibit evidences 
of the effect of pressure. The large crystals are granulated and the 
rock’s structure is more or less schistose. For this aplitic rock with 
porphyritic crystals the author, Chelius, used the name Alsbachite. 
An analysis of an alsbachite from the northwest side of the mountain 
= gave: 
SiO, AlO, Fe,0, FeO MnO CaO MgO K,O NaO H,O 
7413 12.61 287 86 16. 1.60, 28, 213 .456. 6 
The dioritic aplites, malchite, luciite and orbite are also represented 
among these dyke rocks—the malchite being the panidiomorphic 
diorite aplite, the luciite the hypidiomorphic granular forms, and the 
orbite the corresponding porphyritic phases. One of the luciites is 
described as made up almost exclusively of plagioclase and horn- 
blende. Among the lamprophyric dykes, mention is made of a 
gabbrophyre, or odinite, which differs from the gabbro-aplite, beer- 
bachite, in consisting of phenocrysts of plagioclase and colorless augite 
in a matrix of plagioclase laths and hornblende needles, while the 
aplite is a panidiomorphic aggregate of diallage and feldspar, with the 
addition, sometimes, of hornblende crystals that enclose the other con- 
stituents. The descriptions of all these rare rocks are very brief. 
of 185 hand specimens of stock and dyke granites and pegmatites, cuts 
ting the archean and paleozoic beds of Argentina, and of younger 
granites cutting these older ones, 
the origin of the micropegmatitic 
exhaustive, it contains no points of spe 
of the paper is a list of the specimens exa 
° Neues Jahrb. J. Min., etc. B. B. viii, p. 275. 
mined, with their localities, 
