239 



of cubic crystals in phyllitcs and ([iiartzites of the Wai Miha region, 

 whence also psendomorplioscs of linionilo originate. 



Quartz was fonnd in limpid and dull-white crystals, attaining a 

 length of 9 cm., found near Pela, situated between the Wai Miha 

 and the Wai Ha. The shapes are the usual combinations of aoA*. 

 R and — R. 



Calcite. Elegant skalenhedrons /l3 were found in a concretion, 

 originating from the river Kempa, a tributai'y of the river Wai 

 Miha, and likewise in a cavity of a geode Avith MacroceplutUtes. 

 Small rhombohedrons are present in the cavity of the chamosite-rock 

 in the neighbourhood of the mouth of the Wai Nnjo. 



Rlwdoclirosite occurs in the shape of small rhombohedrons on the 

 walls of the air-chambers of a Macrocepkaïites from the Betino. 



Siderite was detected in a boulder of quartzite, originating from 

 the upper-course of the Wai Miha, in the shape of yellowish rhom- 

 bohedrons. Brown rhombohedrons together with calcite were found 

 in the chambers of an Ammonite from the Wai Galo. 



Barite. All the chambers of Macracephalites kee,uwenis G. Boehm 

 are sometimes filled with limpid barite in such a way that the 

 whole mass forms one individual. 



Chemistry. — "Studies in the Field of Silicate- Chemistry." II. 

 On the Lithiumaluminiamsilicates ivhose composition corresponds 

 to that of the Minerals Eucryptite and Spodumene. )iy Prof. 

 F. M. Jae'ier and Dr. Ant. Simek. (Communicated by Prof 

 P. VAN Romburgh). 



(Goinmunicaled in llie meejing ol' May '60, 1914). 



§ 1. In connection with the study of the ternary system, whose 

 components are: llthiamoMde, alumina and .silica, it was necessary 

 for us. to obtain the compounds, whose composition corresponds 

 with that of the minerals eucri/ptite and spodumene, in a perfectly 

 pure state, and to investigate their characteristic properties. The 

 third ternary compound, corres|)oniling in its composition with the 

 mineral petalite, will be taken in account only afterwards, as for some 

 reasons it is better to deal with it, when the experimental study of 

 the ternary mixtures themselves shall have proceeded some-what further. 



The eucrypiite: LiAlSiO^ belongs to the series of silicates, whose 

 other membei's are: nepheline, kaliophiUte, etc. In nature the said 

 compound occurs in the form of microscopical, hexagonal crystals, e. g. 

 in the albite of Brancheville (Conn.); albite and eucryptite both take 

 tlieir origin here from spodumene, decomposed by solving agents. 



