PETROLOGICAL ABSTRACTS AND REVIEWS 705 



ScHNEiDERHOHN, Hans. "Beitrage zur Kenntnis der Erzlager- 

 statten und der geologischen Verhaltnisse des Otaviberglandes, 

 Deutsch-Siidwestafrika," Abhandl. d. Senckenhergischen Naturf. 

 GeselL, XXXVII (1921), 221-321. Figs. 16, figs. 40 in photo- 

 gravure, and colored map i. 



The greater part of this report is economic and geologic. Only a few- 

 igneous rocks are mentioned, namely, aplite, olivine and mica kersantites, and 

 microgranite. The aphte occurs in a dike-like mass widening into lens-shaped 

 masses in several places. It is cut by the younger kersantite. The micro- 

 granite forms a laccolite intruded between strata of the dolomite, and in all 

 probability was derived from the same source as the apUte which may represent 

 the channels through which the larger mass was intruded. 



ScHURMANN, H. M. E. "Beitrage zur Petrographie der ostlichen 

 arabischen Wiiste Agyptens," Centralbl.f. Min., Geol., etc., 1921, 

 449-58, 481-90. 



Very brief descriptions are given of the various igneous rocks of Gebel 

 Mogul, between Gebel Mogul and Um Dalfa, and between Gebel Gharib, 

 Gebel Dara, and Gebel Mogul. Neither chemical analyses nor modal per- 

 centages are given, though the various minerals are named. The rocks de- 

 scribed are various granitites, pegmatitic granite, hornblende-syenite, and 

 tonalite as plutonic rocks occurring in stocks; pneumatolytic granite, granite- 

 pegmatite, quartz-diorite, and quartz-augite-diorite, plutonic rocks in dikes; 

 pegmatite, graphic-granite, quartz, aplite, riebeckite-aplite, quartz-bostonite, 

 malchite, minette, augite-kersantite, amphibole-vogesite, granite-porphyry, 

 riebeckite-granite-porphyry, and quartz-diorite-porphyrite in dikes; and the 

 following extrusive rocks, also in the form of dikes: granophrye, quartz- 

 porphyry, riebeckite-quartz-porphyry, felsite-porphyry, various porphyrites, 

 andesite, diabase-porphyrite, and diabase. 



Schuster, Ernst. " Calcitfiihrende Auswiirflinge aus dem Laacher 

 Seegebiet," Neues Jahrb., B. B. XLIII (1919), 295-318, pis. 2. 



The calcite-rich ejected blocks of the Laacher Sea region which occur in 

 the leucite-phonolite-tuff are alkali syenites which must have formed the 

 country rock in the deeps. The calcite is regarded as a magmatic mineral, as 

 is also cancrinite and the rare calcium apatite. The rocks may be called 

 calcite-pegmatites and calcite-syenites. In other fragments melihte was 

 developed as well as calcite. 



