o48 MINEEALOQT. 



scribes both simple forma and twins. Two laws of twinning are re- 

 cogiiizccl : in one tlic twin axis is a rhombolicdral axis ; in the other it 

 is the symmctiical diagonal of a face of the icositctrahedron 808. Three 

 types of galena-crystals are described — the regular, quadratic, and 

 rhombohedrol. The second section is on the '" Krystallotektonik " of 

 galena, in which the author discusses the formation of crystals by 

 addition from without, and their irregularites of growth. The third 

 section desciibes the modes in which the crystals become aggregated.* 



P. W. E. 



V ^ 



Safaeik, Dr. A. Uebcr die chemische Konstitution der natiirlichen 



chlor- und fluorhaltigen Silikate. Pp. 33. 4to. Prague. With 



plate (graphic formula?). Published in Abh. k. boh. Gesell. Wiss. 



for 1874. 



Eefers all natural silicates to the type Si (OH)^, in which the tetra- 



tomic silicon is combined with four molecules of the monad radical 



hydroxyl. In those silicates which contain chlorine and fluorine, these 



monatomic elements appear to replace the group (OH). Discusses the 



chemical constitution of sodalite, microsommite, eudialyte, pyrosmalite, 



passauite, topaz, leucophane, chondrodite, apophyllite, and tourmaline. 



P. W. E. 



Sandbergee, p. [Huantajayite.] N. Jahrb. Heft ii. pp. 172-174. 



Letter giving results of scientific work at Wiirzburg during 1873, 

 and including a notice of Eaymondi's new species Huantajayite^ a 

 double chloride of sodium and silver, occurring in cubic crystals at 

 Huantajaya in Southern Peru. P. W. E. 



. [Purple copper-ore, &c.] N. Jahrb. Heft vi. pp. 606- 



608. 



Eecords occurrence, and gives analysis of purple copper-ore front 

 near Wittichen, believed to be the only known occurrence of this 

 mineral in the Black Porest. Also contains notes on titanic iron-ore 

 from the Kaiserstuhl, Buchonite (a rock) from near Weiler, " aspa- 

 ragus-stone " from the Zillerthal, &c. P. W. E. 



. [Clarite.] N. Jahrb. Heft ix. p. 960. 



Letter calling attention to new species from the Clara mine, in the 

 Hinterrankach, to be called Clarite. A qualitative examination showed 

 the presence of copper, antimony, arsenic, and sulphur. It appears to 

 crystallize in tlie rhombic system. P. W. E. 



ScHAEEF [?Dr. P.] Ueber den Quarz. Die TJebergangsflachen. 

 Pp.42. 4to. Prankfurt a. M. 



. Weiteres liber Sericit. N. Jahrb. Heft iii. pp. 271-273. 



Describes occurrence of Sericite in the tunnel of Eppstein, and dis- 

 cusses whether this mineral is a definite species or not. 



ScHEEEER, Th. Pebcr die Bildung der erzbegleitendcn Mincralien. 



[On the formation of minerals accompanving ores.] Pogg. Ann. 



Jubelband, pp. 314-321. 



