292 Professor T. G. Bonney & Rev. H. H. Winwood — 



reflected light, their colour being more of a very dark brown than 

 black, but they give a black streak, with a faint undertint of blood- 

 red, so I expect they are really magnetite with slightly oxidized 

 surfaces. Kyanite, if I rightly identify it, is present in rather 

 elongated prisms, also a few minute prisms of a slightly bluish-green 

 mineral, with a high refractive index and a straight extinction, which 

 is almost certainly tourmaline, and a small, rather acicular, brownish 

 mineral, not unlike rutile. 1 Thus the rock is a quartz-mica schist 

 rather than a gneiss, and has evidently undergone some shearing, 

 though the quartzes do not show strain shadows. 



^J Of five specimens (collected as generally representative) from 

 the stream bed above Carrara and below Miseglia, one has the aspect 

 of a much crushed gneiss, with a rude but distinct cleavage. In 

 colour it is whitish, with lead-coloured spots, and on its external 

 flattened surfaces are ' smears ' of a similar coloured mica. Microscopic 

 examination shows the rock to consist of quartz, in grains often 

 slightly elongated, from about "02 in. to "001 in. in diameter; the 

 larger often having ragged edges. Flakes of an almost colourless 

 mica, giving bright polarization tints, occur between the grains, 

 especially the larger, their length being from about *006 in. 

 downwards. Granules of an iron oxide, similar to that in the last 

 specimen, occur singly and in ' coveys ' with three or four rounded or 

 quadrangular grains of tourmaline, varying in colour from brownish 

 to blue ; also one or two of apatite, and the above-mentioned brownish 

 microliths. A second specimen, which it seemed needless to slice, is on 

 the whole intermediate between the two now described, but the crush 

 surfaces are more irregular than in the former, and the rock is more 

 'mottled' in texture, being traversed by patches of the lead-coloured 

 mica, which has a very silvery lustre. 



A third specimen, evidently crushed, for it exhibits a very rude 

 cleavage, is rather white in colour, and resembles a fine-grained, 

 quartzose gneiss, with a fair amount of silvery mica. But microscopic 

 examination does not reveal any felspar, though the former presence 

 of that mineral may possibly be suggested by a clear grain, containing 

 here and there numerous minute specks suggestive of an aluminous 

 residue, and seemingly having a slightly higher refractive index than 

 an adjacent grain indubitably quartz. The mica resembles that 

 already described, exhibiting a distinct foliation, but not very obvious 

 signs of crushing. 



^[ The specimens described above present a general resemblance, 

 especially under the microscope 2 to the quartz-schists, which not 

 infrequently occur in the Alps. My collection contains specimens 

 obtained at intervals from the south side of the Great St. Bernard to 

 the west one of the Gross Glockner. They are well developed in the 

 Einfischthal, especially near Yissoie and around Zinal, where they 

 not unfrequently contain pebbles, and about Saas Fee, where they 



1 Mr. E. H. Rastall, who has had considerable experience in examining 

 microlithic minerals, informs me that the colouring matter appears to him 

 mainly external and suggests brookite as a possible identification. 



2 It shows the gneissose aspect to be illusory, the apparent felspar granules 

 being due to pulverization of the quartz. 



