PETROLOGICAL ABSTRACTS AND REVIEWS 83 



clase filling the interstices between the dark minerals. The quartz-bearing- 

 hornblende-gabbro consists of green hornblende, dark-brown biotite, and white 

 plagioclase. No percentages are given but the statement is made that "the 

 first one still predominates to a greater amount than the other (sic)," probably- 

 meaning the dark exceeds the light. The plagioclase is said to have refractive 

 indices of 1.550 to 1.573 in different crystals, indicating andesine to labradorite. 

 Quartz is accessory, as is also apatite, pyrite, and magnetite. The quartz- 

 diorite has a thickness of not more than one meter and grades into the under- 

 lying gabbro. It consists of quartz, andesine, hornblende, and biotite, with 

 accessory apatite, titanite, zircon, magnetite, and pyrite. If, then, this mass 

 represents a single body, which has been differentiated, it indicates the manner 

 of the separation of the various minerals. "In the dentral and lower part 

 olivine and hypersthene are present, and large crystals of hornblende enclose 

 all other constitutents, indicating .... that it was the last phase in the course 

 of consolidation of the magma at this part. Towards the upper layers, olivine 

 and hypersthene decrease in amount and finally disappear in the hornblendite. 

 Here augite decreases in quantity and ceases to show the poikilitic relation to 

 hornblende, while plagioclase appears filling up the interstices of the femic 

 (sic) minerals. In a still upper part formed of gabbro, plagioclase becomes a 

 member of the essential ingredients. A prominent feature of this part is, how- 

 ever, the appearance of quartz, though it is small in quantity. Here this 

 mineral is the phase which was last to crystallize out. Further, approaching 

 the upper marginal part, plagioclase and quartz increase in quantity and form 

 the essential components." 



No modal percentages are given but there are chemical analyses of the 

 first three rocks. 



Weise, E., and Uhlemann, A. "Sektion Auerbach-Lengenfeld," 



Erldut. geol. Spezialk. Konigr. Sachsen. Leipzig, 191 5, 2d ed. 



Pp. 57, figs. 3. 



This quadrangle contains the three large granite masses of Bergen-Lauter- 



bach, Eibenstock, and Kirchberg, between which are slates, phyllites, and 



quartzites, metamorphosed by the granite. Various analyses are given, the 



contact action is described, and the associated dikes of aplite, kersantite, and 



mica-porphyrite are discussed. Two bowlders of melilite-nepheline-basalt 



were found at the eastern border of the quadrangle, but the source could not 



be discovered. 



Weiss, Gustav. "BeitragezurpetrographischenErforschungdes 



Unteren Buntsandsteins," Ber. d. Oberh. Ges.f. Natur. — u. Heil- 



kunde. N. F. Naturw. Ahtlg., VI (1914). Pp. 14, pi. i, figs. 2. 



The quartz-feldspar-sandstone at Gisselberg, near Marburg, consists of 



20 to 30 per cent feldspar and 70 per cent quartz. The feldspar is about half 



