THE METEORIC PERIDOTITES. — LHEKZOLITR 99 



black color; and by the ramose or branching structure of the meteoric iron. Nearly 

 one-half of the chrysolite, however, is more massive, approachin*^ fimt-j^anular, or com- 

 pact. Yet in tliis condition it is still highly crystalline, and difticnltly frangible. This 

 portion is of an ash-gray, flecked with specks of a dull greenish-yellow color. Tlie 

 lustre is feebly shining. . . . Especially is it observable that the stony portions nowhere 

 present traces of the oolitic, or semi-porphyritic structure, so common in meteoric 

 stones. . , . 



" The meteoric iron, besides being in ramose branches, is also in enveloping coatings 

 around the chrysolite, somewhat as in the Pallas and Atacama irons, . . . The 

 presence of schreibersite in the metal is apparent to the naked eye." The minerals that 

 Shepard supposed that he found were chrysolite, schreibersite, chromite, troilite, a " felds- 

 pathic mineral, presumably anorthite," and an " opal-like mineral of a yellowish-brown 

 color, which I take to be chassignite." 



Later, J. Lawrence Smith made a further examination of the Estherville meteorite.* 

 He found olivine, broiizite, nickeliferous iron, troilite, chromite, and an opalescent silicate. 

 The last has a light, greenish-yellow color, and cleaves readily. It was regarded as 

 formed from one atom of bronzite plus one atom of olivine. Smith further says : " I 

 examined carefully for feldspar and schreibersite, but the absence of both lime and alu- 

 mina (except as a trace) clearly proved the absence of anorthite ; and the small j)anicks 

 of the mineral that might have been taken for schreibersite, were found on examination 

 in all instances to be troilite." 



Dr. Smith's chemical analysis was made in such a manner that it is impossible from 

 it to draw any conclusions as to the relative proportion of the elements in the mass as 

 a whole. 



Later,! Smith named the " opalescent silicate" ^^ccMrt^HzYc, and thought from his 

 farther analyses that it was probably composed of two atoms of bronzite to one of oli- 

 vine 



In 1882 Dr. Stanislas Meunier described the microscopic characters of the Estherville 

 peridotite, which he referred to the logronite type of meteorites — one of the 43 types 

 proposed by him in 1870. % He found the following minerals : olivine, bronzite, pcd- 

 hamite ? pyrrohotite, schreibersite, magnetite, and nickeliferous iron. 



The olivine is in very large crystalline fragments, yielding in polarized light a most 

 brilliant colored mosaic. In common light they are colorless, often cleaved and tilled 

 witli crystalline inclusions. Liquid bulibles in spheroidal cavities, remarkable for their 

 large size, were seen. In converging light the crystals show two systems of brilliant 

 rings, whose axes show strong dispersion. 



The bronzite is in poorly formed crystals, clearly dichroic, and showing a well-marked 

 parallel rectilinear cleavage. 



The pcckhamitc is in large, feebly colored crystals, composed of alternations of lamime, 

 inversely affecting polarized light. The action of acids upon them causes one to regard 

 this mineral as composed of extremely thin interlaminated layers of bronzite and olivine. 



The magnetite is in perfect octahedrons. 



M. Meunier concludes as follows : " In presence of these different characters of com- 

 position and structure, it is seen that the identity is complete with the logronite already 



* Am. Jour. Sci., 1880 (3), xix. 459-103, 195, 190. 



t Am. Jour. Sci., 1880 (3), xx. 130, 137. 



+ Cosmos, 1870 (3), vi. 70-73, 95-98, 152-155, ISO-ISS, 210-:J15. 



