PETEOLOGr. 207 



and homblendic Andesito from Toplitia, near Gyorgy St. Miklos, 

 in Transylvania.] Yerh. k.-k. geol. Eeiclis. pp. 120, 121. 

 Gives the physical, chemical, and microscopical characters of the 

 Andesite. 



John, K. Analyse eines Hornblende- An desits von Tusnad am Biidos 

 bei Kronstadtin Siebenbiirgen. [Analysis of a hornblendic Ande- 

 site from Tusnad, on the Biidos, near Kronstadt, in Transyl- 

 vania.] Yerh. k.-k. geol. Reichs. pp. 242-244. 

 Points out that the rock, though regarded by Dr. G. Stache as a 

 " Sanidine-oligoclase-trachyte," is really a hornblendic Andesite, as 

 shown by analysis and microscopic investigation. H. A. N. 



JrBD, J. W. Scotch Yolcanic Rocks. See p. 22. 



Kaikowskt, Ernst. Die augithaltenden Felsitporphyre bei Leipzig. 

 Zeitsch. deutsch. geol. Ges. Bd. xxvi. Heft 3, pp. 586-599. 



Augitic felsite-porphyry occurs between Wurzen, Grimma, and Bors- 

 dorf, near Leipzig. The rock is composed of quartz, orthoclase, labra- 

 dorite, augite, biotite, titanic iron-ore, magnetite, and apatite. Each 

 component is described in detail. The composition and colour of the 

 porphyry vary ; and the nature of the enclosures appears to vary with 

 the composition : the more augite and plagioclase, the more glass- 

 cavities ; the more quartz and orthoclase, the more fluid-cavities. Com- 

 position of the rock varies geographically — the more basic varieties oc- 

 curring in the east, the more acid in the west. The felsitic base is a 

 fine-grained crystalline aggregate of quartz, two felspars, and augite. 

 The base exhibits fluid structure. Concretions of dark and pale- 

 coloured felsite occur in the porphyry. P. \Y. R. 



. Mikroskopische Untersuchungen von Eelsiten und Pechsteinen 



Sachsens. [Felsites and pitchstones of Saxony.] Min. Mitt. 

 Heft 1, pp. 31-58. 

 Describes microscopic structure of pitchstones, felsites, and felsite- 

 porphyry from Saxony, with special reference to the character of the 

 ground- mass. F. W. R. 



Kenngott, a. N. Jahrb. Heft 5, pp. 515, 516. 



Letter describing a concretion found loose near Brigels, in Switzer- 

 land. It consists of a crust of actinolite, enclosing a kerjiel of green 

 granules and crystalline needles; the surface is coated with biotite. 

 An attached fragment shows that the matrix was a fine-grained 

 granite. F. \Y. R. 



. [Pitchstono and Obsidian.] N. Jahrb. Heft 6, pp. 608-611, 



2 woodcuts. 



Describes microscopic section of pitchstone from Garesbach, near 

 Meissen. One of the disseminated crystals of orthoclase encloses a 

 banded concretion. Elongated tube-like bodies, of irregular branch- 

 ing form, are also present in the pitchstone. The black obsidian from 

 Hecla, previously described by the author, loses its coloui' on heating, 



