THE METEOEIC PEEIDOTITES. — BUCHNEEITE. 101 



those of a sponge-like ii-on mass holding silicates, those of but little iron with the sili- 

 cates, and those that are pure or nearly pure silicates. If detached portions should be 

 taken and analyzed chemically and microscopically, it could be claimed that this meteorite 

 is a siderolite — a pallasite — a peridotite, and all be equally correct so far as the portion 

 examined would show; but studying this meteorite as a whole, its proper place both 

 chemically and microscopically appears to be witli the peridotites. The variations in the 

 descriptions given by tlie diflerent observers who have examined this meteorite, are 

 doubtless owing, m many cases, to tlie actual variation in the rock itself. It offers a 

 striking illustration of the need of souie more general method than a purely mineralogi- 

 cal one in naming rocks. 



Since the preceding was written, specimens of this meteorite, containing peckhamite, 

 have been received from Professor Peckham. The sections present for the mass of the 

 meteorite the same composition and structure as those obtained from Professor Hall. 

 The peckhamite presents the optical characters and cleavage of enstatite, but is filled 

 entirely full of vapor cavities, iron, glass, brown grains, etc. To these inclusions is appar- 

 ently owing the coloid appearance of peckhamite, and the variation iu its analysis ; while 

 Meunier probably mistook plagioclase for this mineral. 



Variety. — Buchnerite. 



Tieschitz, Moravia. 



A microscopic study of the Tieschitz meteorite has been made l>y A. Makowsky and 

 G. Tschermak. The color of the meteorite on its inner surface is ash-gray, and it has 

 a chondritic structure. It shows many minute deep-gray, or dark-colored globules and 

 splinters, and occasionally larger spherules of the same color ; also, little white globules 

 and fragments, which are subordinate in amount to the former. Lying between them 

 were seen an ash-gray earthy groundmass, and a very few yellowish particles showing 

 metallic lustre. Certam characters of some of these spherules had never been described 

 previously in any other meteorite. Some show a concave impression upon them, indi- 

 cating plasticity during their formation. Some of these latter spherules also show out- 

 side of these concavities an excrescence having a round or pointed termination. These 

 characters not harmonizing well with Tschermak's friction theory of the formation of 

 the globules, which will be later given in this work, (pp. 109, 110), he adopted a new 

 theory, that while these grains are the result of volcanic eruption and explosion, their 

 form could be derived from their plastic condition, instead of from the friction of solid 

 particles as he had held before. 



The general characters of the meteorite were much the same as those of tlie preced- 

 ing. Olivine, bronzite, enstatite, augite, pyrrhotite, and nickeliferous iron were the min- 

 eral constituents observed. 



The olivine was found in the groundmass, and in some of the spherules. Inclusions 

 of black angular gTams, and of brownisli glass with fixed bubbles, were seen. 



The bronzite is principally in stalk-like and fibrous forms. It contains also inclus- 

 ions of brown glass, with immovable bubbles. 



The enstatite has about the same form as the bronzite, contains the same inclusions, 

 and is white or of a pale color. It occurs in chondri and fragments. Augite was found 

 in small amounts in globules, having the same inclusions as the olivines. 



