508 Br. Walter Flight— On Meteorites. 



tree, traverses the whole stone, and gives ns the impression that 

 they are the result of the blow which the meteorite received on its 

 fall. The mass of the stone is brittle, the colour blackish grey with 

 bright points. There are many inclosed mineral particles, some 

 almost invisible, others 1 cm. across, the greater part having a 

 diameter of less than 2 mm. The matrix is black and opaque even 

 when viewed in a microscopic section, and many of the inclosed 

 particles are opaque or only translucent in points. Most of them, 

 however, are transparent, and the majority have a circular or rounded 

 outline. A plate is appended to Tschermak's paper showing figures 

 of the inclosed minerals. Five distinct ingredients could be dis- 

 tinguished. The first is a clear greenish mineral, with incomplete 

 cleavage along two directions perpendicular to each other, and 

 identified as olivine. A second in round tough spherules, brownish 

 in hue and not numerous, with a finely foliated or finely fibrous 

 structure, was found to be bronzite. Inclosed particles are some- 

 times made up of these two minerals, sometimes, but not very fre- 

 quently, of them together with a third silicate in long greenish 

 prisms which have the appearance and angles of augite. The me- 

 teorite also contains some magnetic pyrites (troilite?), a very little 

 nickel-iron and j)erhaps a little carbon, to which the dark hue of the 

 matrix is due. 



Tschermak directs attention to two peculiarities observed in several 

 chondritic meteorites, and noticeable in this one. The first is the 

 occurrence of a crust over the surface of the bronzite spherules, 

 possessing fibrous structure. This crust is thin, and is distinguished 

 from the inclosed material by its jDaler colour ; it has the same 

 fibrous structure, doubly refractive power, and, in fact, is optically 

 orientated like the inclosed silicate. It apj^ears to be produced by 

 some agent acting from without, perhaps heat in conjunction with 

 a reducing gas. The agent has not caused fusion, but a slight 

 modification of the texture of the surface. The second point which 

 he has observed is the distribution in zones of the magnetic pyrites 

 in many of the granular inclosed masses. When a microscopic 

 section is examined by reflected light, it is found that many are 

 apparently surrounded by a crust of the metallic sulphide, in others 

 it occupies the centre of the mass, in all cases apparently filling up 

 interstices. It seems as if the sulphide had impregnated the rocky 

 mass, and the absence of all magnetic pyrites in the very compact 

 inclosed particles, and the tough fibrous bronzite chondra, confirms 

 this view. This impregnation Tschermak believes took place after 

 the inclosed mineral particles attained their present form, and the 

 only exj)lanation which can be suggested is that this must have 

 happened while the whole tufaceous mass was strongly heated. 

 According to this theory, the inclosed granules coming in contact 

 with fused magnetic pyrites must have drawn it into the fine fissures 

 and interstices, in some instances into the cavities of the granules 

 themselves. 



This argues the existence of two definite stages in the formation 

 of these and similar chondritic structures. First, the production of 



