The rocky peak of the Riffelhorn (9616 feet), well known to all who have visited Zermatt and the Gornergrat, forms part of a large mass of serpentine which seems to vary slightly in composition and is generally more or less schistose, becoming in places quite slaty—the effect of pressure. On the summit of this peak the compass, as is well known, exhibits the most extraordinary variations, and the ... [Show full abstract] rocks appear to be not seldom struck by lightning. Specimens exhibiting fulgurites were collected on it by both Prof. W. Ramsay and Mr. J. Eccles in 1890, the examination of which has led to ,some, interesting results.
The geologist, in working over different parts of. this large mass of serpentine, observes that, where the original structure is not obscured by subsequent pressure, the rock is not quite uniform in character—one variety being an ordinary dark green bastite-serpen-tine (sometimes also containing augite), the other being a little tougher and harder under the hammer and slightly rougher when handled; in short, it is not quite so normal a serpentine as is the other variety. Of this harder kind the upper part (at any rate) of the Riffelhorn peak is composed.
It will be convenient to speak of the microscopic structure and chemical composition of the rock before describing the effects of the lightning, though the latter was the reason that induced Prof. Ram say to ask the present authors to investigate the former questions.
Slices for microscopic examination were prepared from