198 PETBOLOGY. ' 



Anon. Ninth Annual Eeport on the Colonial Museum and Labo- 

 ratory. New Zealand, 1874. Pp. 35. 



The Laboratory Report contains 10 analyses of New-Zealand coals, 

 14 of limestones and other rocks, 7 of iron-ores, several assays of gold 

 and antimony-ores, and an analysis of mineral water from the Province 

 of Napier. P. W. E. 



[On Andernach Trass.] Stoompost, 1874. 



Trass is a tuffstone, found in the Eifel ; the principal quarries are in 

 or near the valley of the Brohl and the Nette, close to Andernach. The 

 tuffstone is a volcanic ash, underlying pumice-stone ; it contains from 

 50 to 60 per cent, of silica and only from 5 to 10 per cent, of lime. 

 The silica is partly in a soluble state, forming with lime and water a 

 silicate of great hardness. (From abstract in Proc. Inst. Civ. Eng. 

 vol. xxxix. pp. 313-316.) "W. T. 



Bakonowski, Joseph J. Die mineralogische und chemische Zusam- 

 mensetzung der Granitporphyre. Zeitsch. deutsch. geol. Ges. 

 , Pd. xxvi. Heft 3, pp. 522-532. 

 Describes the mineralogical and chemical composition of granite- 

 porphyry from near Leipzig and from Altenberg, in Saxony. The base 

 consists of crystalline granules of quartz, felspar, hornblende, and 

 chlorite, with magnetite and apatite. ■ Its structure is therefore granitic, 

 and thus essentially different from that of felsite-porphyry, in which 

 the base is amorphous. The minerals forming the base separate out in 

 distinct crystals. Sharply defined crystals of quartz have not been 

 observed in any similar rock ; if the quartz is crystallized, as in felsite- 

 porphyry, the base is amorphous ; if the base is crystalline, as in granite, 

 the quartz occurs only in irregular angular granules. The felspar is 

 partly orthoclase, partly plagioclase. Glass-cavities occur in both 

 quartz and felspar ; it is notable that they had not been previously 

 observed in rocks with a crystalline base. Analyses are given of granite- 

 porphyry from Beucha, near Leipzig, and from Altenberg. P. W. R. 



Pertels, G. a. Ein neues vulkanisches Gestein. [New Yolcanic 

 Pock]. Yerh. Wiirzburg. phys.-med. Ges. viii. pp. 32. [Noticed 

 in N. Jahrb. Heft 8, pp. 873-875.] 

 A rock described by Sandberger as a nosean-andesite has been ex- 

 amined by Pertels, who regards it as a new species. A typical example 

 of the rock occurs at the Seugelberg, near Salz. It is a felspar-and- 

 hornblende rock, containing nosean and nepheline ; but the felspar is 

 purely triclinic. Chemical analyses of the rock are given. Pertels pro- 

 poses to distinguish it as Isenite, from the Piver Eis (Isena). The 

 hornblende becomes altered to a mineral which appears, from its ana- 

 lysis, to be a new species of the chlorite group, named by Pertels pJicv- 

 actinite. F. W. P. 



BoEiOKT, E. Petrographische Studien an den Phonolithgesteinen 

 Bohmens. [Phonolites of Pohemia.] Arb. geol. Landesdurch. 



