112 



WEIGAXD treated the powder of the rock with weak hydrochloric acid for 

 several days. 3'678 grammes gave '2599 of a residue which consisted almost 

 entirely of the mineral. 



i. n. in. iv. 



SiO a ... 37-7" Mi ... 31-098 ... 36-944 ... 46-407 



A1 S 3 ... 0-201 ... 12-701 ... 1-353 ... 6-727 



Fe 2 3 ... 10-428 8'847 ... 6-868 ... 4-641) 



FeO ... ... ... 3-956 ... 2-107 



CaO ... 1-677 ... 5-470 ... 1-393 ... 10-642 



MgO ... 36-602 ... 26-714 ... 36-022 ... 26-252 



H 8 ... 13-386 (diff.) 15-170 (cliff.) 13-089 3-584 



100-000 100-00 99-625 100-368 



T. Soluble portion of Kauentlial serpentine. 



II. Insoluble ditto 



III. Bulk analysis of ditto 



IV. Bulk analysis of adjacent ampliibolite containing a little serpentine. 



The analysis of the soluble portion corresponds to a. serpentine containing 

 iron-oxide. That of the insoluble portion shows that the silvery talc-like 

 mineral is a chlorite. The rock analysed is a mixture of serpentine, chlorite 

 and iron-oxides. The bulk-analysis of the adjacent amphibolite shows that 

 it is mainly composed of hornblende rich in magnesia. 



The author concludes that the Raueiithal serpentine has been formed by 

 the alteration of a hornblende rock, and that the change has been accompanied 

 by the removal of lime and the developement of a chlorite in which the 

 original alumina of the hornblende is retained. 



Passing over several papers (1) in which the views of authors previously 

 quoted are confirmed and extended, we now come to an important 

 communication by Dr. HUSSAK (2) " Uber einige Alpine Serpentine." The 

 rocks investigated by this author belong in part to the Wiudisch Matrey type, 

 first described by DRASCHE, and in part to normal oliviue-serpentines. The 

 former only need be referred to here. 



In the neighbourhood of Sterling, on the Brenner route to Italy, several 

 isolated exposures of massive and schistose serpentine occur along an east 

 and west line ; that is along the strike of the schist with which the 

 serpentine is associated. At the Sattelspitz the relations between the 

 serpentine and the schists (calcareous phyllites) are well exposed. Lenticular 

 masses of serpentine, talc and magnesite occur in serpentinous schists which, 

 in turn, are conformably interbanded with the calcareous phyllites. Lenticles 

 of massive serpentine, also in association with talc and magnesite, occur in 



(1) A. LAGOIUO. Mikroskopisclic analyse ostbaltischeii Gebirgsarten. Dorpat. 1876. p. 4o. 



E. KALKOWSKY. Die Gneissformation des Eulengebirges. Leipzig. 1878. p. 43. 



F. BECKE. Gesteine aus Greicheriland. T.M.M.. 1878. p. 4o9. 

 (-2) T.M.M. Noue Folge. Vol. V., p. 61. 



