154 Dr. Walter Flight — History of Meteorites. 



Tsckermak examined two microscopic sections of the Ovifak rocks, 

 and compared them with sections of the meteorites of Jonsac, 

 Juvinas, Petersburg, and Stannern, which consist chiefly of augite 

 and anorthite, with little or no nickel-iron ; they form a class which 

 G. Eose termed 'eucritic.' Both sections exhibit a crust, as meteorites 

 possess ; it is, however, so altered by oxidation, that it is not possible 

 to determine whether it is the fused crust usually noticed on a 

 meteorite. The crystals of felspar, which, according to Nauckhoff' s 

 analyses, must be regarded as anorthite, are fully developed ; they 

 penetrate the augite, iron, and magnetite, and must evidently have 

 been formed before them. They are completely transparent, and 

 have but few and large cavities, which are filled, partly with black 

 granules, partly with a Jbrown substance of irregular form ; some 

 traversing the length of the crystals are filled with a transparent 

 glassy substance. The augite is of a light greenish-brown hue, 

 traversed here and there by flaws ; it fills gaps between the other 

 constituents, as has been often observed in dolerites and diabases, 

 and encloses individual black grains. In the section containing iron 

 the colourless felspar encloses a black or brown substance running 

 the length of the crystals, or dust-like fine black granules, or larger 

 round transparent bodies of a violet colour, which may be the 

 mineral Nauckhoff regards as spinel. Side by side with the felspar, 

 brown grains, less numerous than in the former section, are seen, 

 and these are probably augite. Black particles, moreover, occur, 

 which by reflected light appear to be semi-metallic, and are probably 

 magnetite, as well as others that are likewise black, but devoid of 

 lustre, which seem to be graphite. A few small grains of troil,ite 

 were also recognized. In the second section, which bore a general 

 resemblance to the first, the felspar crystals were larger, the 

 matrix being made up of finer crystals. In some of the felspar 

 crystals cloudy pale brown patches were observed, which, when 

 viewed with a higher power, were found to be due to numberless 

 minute elongated inclosed granules tying in parallel position, or to 

 others that were shorter and more rounded. These appearances recall 

 those noticed in eucritic meteorites, like that of Jonsac, except for 

 the fact that the inclosed particles are of smaller size. The larger 

 cavities in the felspar are filled in the same manner as in the other 

 rock section from Ovifak. The structure of eucritic meteorites is 

 tufaceous ; that of the Ovifak rock very compact. This distinction, 

 however, has often been observed in meteorites. Many chondritic 

 meteorites are tufaceous ; while others, having similar chemical com- 

 position, like the aerolites of Lodran and Manbkoom, are compact 

 and crystalline. The augite of the Ovifak rocks has not the charac- 

 teristically filled cavities observed in that of certain eucritic meteor- 

 ites ; but in the augite of some meteorites, as those of Shergotty and 

 Busti, for example, they are equally wanting. 



The meteorites of Ovifak in some respects resemble the carbona- 

 ceous meteorites, though they differ greatly from them in other 

 characters : especially in the appearance of both metallic and rocky 

 portions. They form a new type in the series of meteoric rocks, 



