PETROLOGICAL ABSTRACTS AND REVIEWS 627 



grains of cassiterite. In his conclusion the author presents a brief 

 summary of the geologic history of the region about Gopeng. 



Heath M. Robinson 



Skeats, E. W., and Summers, H. S. "The Geology and Petrology 



of the Macedon District," Bull. Geol. Surv. Victoria. Victoria, 



191 2. Pp. 58, map, and pis. 28. 



The granodiorite of this region is shown to be intruded into the dacite, 



and an altered zone was found in the dacite at its contact with the 



granite. Two new rock types, macedonite and woodenite, are described. 



They somewhat resemble orthoclase basalts and have some characters in 



common with mugearites. A number of rocks previously determined by 



Professor Gregory are here redescribed. Twenty-nine analyses of 



igneous rocks are given and computed in the Cross, Iddings, Pirsson, 



Washington system. 



" A. J. 



Skeats, Ernest W. "The Occurrence of Nepheline in Phonolite 

 Dykes at Omeo," Australasian Asso. Adv. Sci., XIII (1912), 

 126-31. 



Stewart, Charles A. "The Geology and Ore-Deposits of the 

 Silverbell Mining District, Arizona," Bull. 65, Amer. Inst. Min. 

 Eng., 1912, 455-505- 

 Among the igneous rocks described are alaskite, alaskite porphyry, 

 biotite granite, quartz porphyry, andesite, rhyolite porphyry, horn- 

 blende andesite porphyry, and an almost pure quartz rock. 



A. J. 



Tyrrell, G. W. "The Late Palaeozoic Alkaline Igneous Rocks of 

 the West of Scotland," Geol. Mag., IX (191 2), 69-80, 120-31. 

 The writer divides the late Palaeozoic intrusive rocks of the west of 

 Scotland into three groups, those with conspicuous analcite, those with 

 conspicuous nephelite, and those without conspicuous analcite or 

 nephelite, but which may contain either or both as accessories. Among 

 the first class he describes analcite-syenite, teschenite, picrite-teschenite, 

 lugarite, and monchiquite. Lugarite resembles the heronite of Coleman, 

 and is related to leucocratic teschenites and to ijolites. It occurs in the 

 form of a sill 4 feet thick in the Lugar teschenite-picrite complex, and 

 as dikes penetrating the picrite. In hand specimens it shows a grey 

 or greenish-grey groundmass crowded with barkevicite prisms up to 



