220 TETEOLOGY. 



TscHEEMAK, G. [The Meteorites of Orivinio, Borne (1872, Aug. 31)]. 

 Sitzungsb. k. Ak. Wiss. Ixx. 



Devoted to an inquiry into the structure of this stone. It is made 

 up of light -coloured fragments, surrounded with a dark-coloured 

 cementing material. The former are normal ' chondrite, have a yel- 

 lowish grey colour, and enclose spherules and particles of nickel-iron 

 and magnetic pyrites. The latter contains numerous particles of the 

 two last-mentioned ingredients, for the most part uniformly distributed ; 

 the portion nearest the fragments bears distinct indications of having 

 been fluid, and conveys the impression that this cementing material 

 was in a plastic condition while in motion. The Orivinio stone re- 

 sembles certain brecciated volcanic rocks, which consist of a ground- 

 mass through which granular fragments of the same rock are distri- 

 buted, as when older crystalline lavas are interpenetrated by others 

 more compact and more recent. The light-coloured fragments are 

 chondritic ; and among their constituents are olivine, bronzite, and a 

 finely foliated mineral, which may be a felspar. The darker material 

 which coats these fragments and fills the finer flaws between them 

 contains two ingredients — an opaque semivitreous constituent and 

 particles in every way similar to the dark crust of the fragments from 

 which they^finay have been detached; many of them can still be recog- 

 nized as olivine and bronzite. The paper is illustrated with drawings 

 of microscopic sections of the two rock-varieties. ' W. P. 



[The Chantonnay Meteorite (1812, Aug. 5)]. Sitzungsb. k. 



Ak. "Wiss. 



Detects the presence of olivine, bronzite, a finely fibrous translucent 

 mineral, nickel-iron, and magnetic pyrites, and finds that it bears a 

 great resemblance to the meteorite of Orivinio, but contains less 

 iron. The structure is chondritic ; but there are not many sj^herules. 

 Erom an investigation of the black veins, the author thinks that this 

 meteorite, at the time of its formation, was brought into contact with 

 molten material. Although Von Reichenbach held that these veins 

 were intimately connected with the fused crust of the meteorite, it 

 must not be forgotten that, meteorites in their interior have a low tem- 

 perature when they reach the earth ; and an examination of this stone 

 indicates that its fused crust has only penetrated the body of the stone 

 to the depth of 6 mm., the^ clefts in some cases remaining partly open. 

 He points out that the Chantonnay meteorite has a composition differ- 

 ing in no material degree from that of the Orivinio meteorite, the chon- 

 dritic fragments and the dark- coloured cementing material of which 

 were found to have the same composition. The structure of the stone 

 closely resembles that of a metamorphosed breccia. He considers that 

 the Chantonnay and Orivinio stones indicate changes that have occurred 

 on the surface of some planet, which has subsequently been shattered 

 into fragments. . "W. F, 



