580 PETROLOGICAL ABSTRACTS AND REVIEWS 



quartzites are rhyolites, and thorough study would probably change many 

 of the names applied to the igneous rocks. Some are pre-Tertiary, but 

 most of them are Tertiary in age. Among the effusives are andesites, 

 rhyolites, basalts, tuffs, and breccias. The granular rocks occur less 

 abundantly. Those mentioned are granodiorites, hornblende-gabbros, 

 diorites, monzonites, micaceous granites, granite- and diorite-porphyries. 

 The paper concludes with a list of minerals found in the district. 



Charles J. Hares 



Spitz, Albrecht. " Basische Eruptivgesteine aus den Kitzbiichler 

 Alpen," Tscher. Min. Petr. MiL, XXVIII (1910), 497-534. 



In the so-called Silurian schists of the Kitzebiichlian Alps, occur two 

 groups of basic eruptive rocks. One group consists of undoubtedly 

 effusive sheets and tuffs, interbedded with the schists; the other consists of 

 isolated outcrops whose mode of occurrence is indeterminable. 



The rocks described are monzonite-diabase, ordinary and olivine dia- 

 base, diabase porphyrite, hornblende diabase (proterobase), hornblende 

 picrite, proterobase amygdaloid, albite-chlorite schist, and epidote-chlorite 

 schist. The rock of greatest interest is the one to which the writer gives the 

 name of monzonite diabase. With this term he wishes to designate all 

 rocks which carry potash feldspar in greater quantity than is normal in 

 diabases, but does not say that the amounts of orthoclase and plagioclase 

 must be equal. Brauns and Erdmannsdorfer have previously described 

 rocks which contain greater amounts of potash and which are transitional to 

 essexites and theralites. The monzonite diabases differ from essexite- and 

 theralite-diabases in the greater amount of SiOa in the former, so that they 

 are sometimes quartz-bearing and are then related to Kongadiabase. 



The plagioclase in the monzonite diabase is almost pure albite, which 

 the author says is only comprehendable by considering it due to alteration. 

 The potash feldspar occurs in part in irregular patches in the plagioclase, in 

 part as interspaced filling. Much of it is peculiar in having a small axial 

 angle, 2F=48°, and in being optically positive. The pyroxene is enstatite 

 augite (Mg-diopside of Rosenbusch), and is sometimes intergrown with 

 brown hornblende. Ilmenite is present and there is much apatite. The 

 texture is divergent-strahlig-komig (Lossen's term for ophitic). The iron 

 minerals and apatite were the oldest, and quartz and micropegmatite the 

 youngest minerals to form. Pyroxene and feldspar are essentially of the 

 same age, for they mutually inclose each other. 



A chemical analysis of a quartz-free monzonite diabase from Weissen- 

 bachtal near EUmau gives: SiOa 49.86, AI2O3 13.01, Fe^Oj 13.78, 



