456 MISS E. ASTON AND PROF. BONNEY ON [Aug. 1 896, 



Two analyses were made, but both came out a little too high : — 



A. B. 



Si0 2 40-27 40-25 



A1 2 3 3-96 3-26 



Fe 2 3 2-22 295 



FeO 2-69 2-69 



MgO 41-69 41-01 



Na 2 0-71 0-71 



Combined water 9*46 9*56 



Moisture 017 0-17 



101-17 10060 



This is nearer to the analysis of an ordinary serpentine, but the 

 amount of alumina is rather large ; possibly a colourless chlorite 

 may be present among the flaky minerals, as described in the 

 Rauenthal serpentine. 1 



In conclusion, a lightning-struck rock may be noticed which was 

 obtained by Prof. Ramsay on the Hornli (9492 feet), a well-known 

 point of view near the base of the Matterhorn. It is a somewhat 

 prismatic fragment, measuring about 1 j X 1| X 1 J inches. Macro- 

 scopic examination shows that it is a variety of the ' griiner 

 schiefer ' or ' green schist ' of the Zermatt district, very familiar to 

 one of us. 2 



As there is nothing unusual in its aspect, and the lightning-marks 

 would be easily damaged, we have not had a slice prepared. The 

 green mineral in this group of rocks is sometimes chlorite, some- 

 times a more or less actinolitic hornblende ; felspar or some kindred 

 aluminous silicate, epidote, garnet, are often — and glaucophane is 

 occasionally — present. 



On analysis a fragment of this specimen gave the following 

 results : — 



A. B. 



Si0 2 42-80 4309 



A1 2 3 18-53 17-15 



Fe 2 3 7-79 7-85 



FeO 501 5-93 



CaO 11-74 1205 



MgO 8-96 904 



OuO trace trace 



Na 2 trace trace 



Combined water 4*71 510 



Moisture 017 018 



99-71 100-39 



1 Wadsworth (' Lithological Studies,' pp. xxiv-xxviii) quotes 15 analyses of 

 serpentine from nine different localities in the Alps, six of them representing 

 specimens from the Zermatt district. In these analyses the Si0 2 varies from 

 39-7 to 42-8, the MgO from 301 to 41-3, and the H 2 from 93 to 136. 

 Alumina, lime, and nickel are often wanting : the maximum of the first being 

 2-8, of the second 4*7, of the third 0'5. Other analyses, with two of antigorite, 

 are quoted bv Teall in his interesting chapter on serpentine (' British Petro- 

 graphy/ pp/ll3, 114).— T. G. B. 



a Bonney, Quart. Journ. Geol. Soo. vol. xlix. (1893) p. 94. 



