238 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



no more to be doubted. The bright fissured mineral evidently belongs to the augite group. The high percentage of 

 iron protoxide is very unusual, even when we allow for a corresponding portion as united with chromium oxide to form 

 chromite. On the other hand, the small amount of magnesia and lime is noticeable, in contrast. The high percent- 

 age of alkali appears to have more bearing upon the composition of the chondri and to point to a feldspathic consti- 

 tution. If, as appears probable, the alumina belongs to the compound with the corresponding quantity of silicic 

 acid, a corresponding composition of an augite rich in iron appears, such as occurs in the eukrites; for example, that 

 of Juvinas. The exact nature of this augitic compound always seems hard to ascertain. Although the analysis of the 

 Iowa meteorite which J. L. Smith contributed does not agree exactly with the foregoing, still even in this there is an 

 unusually high percentage of iron protoxide in the insoluble portion. 



The chondri have found no more consideration, since they can not, without further investigation, be regarded as 

 as composed of augite. 



Among chondri thus far analyzed, only that of Tadjera has a similar composition, although poorer in silica and 

 rich in lime. 



If the data of all the investigations of this meteorite be combined, they give rise to the following conclusions: 



1. The stony matter consists of irregular splinters of olivine and an augitic substance, which appears to be derived 

 from one disintegrated stone. There also appears to be a feldspathic substance present in small quantities. Finely 

 pulverized particles of this mineral apparently furnish the cementing medium. 



2. The roundish chondri compose, besides the mineral particles alluded to, a considerable portion of the sub- 

 stance of the stone. Sometimes they are connected with the olivines, and sometimes they present lamellar inter- 

 growths of minerals, or consist of radiated fibrous masses. A portion of them seem to consist of a feldspathic substance. 

 Their form is due to mechanical abrasion. 



3. The meteoric-iron grains are so situated between the mineral splinters and the chondri that they appear to have 

 originated by reduction subsequent to the formation of the stone. 



4. There are no glass or lavalike constituents (the fusion crust excepted) in the stone. This is not a rock crystal- 

 lized out of a fused mass, but a clastic one whose constituents do not have the character of a volcanic ash. 



Wright 9> 10 repeated his previous observations on the gases of the meteorite, but reached no 

 especially new conclusions. 



Wadsworth ll gave an optical study of the meteorite, as follows : 



The specimen of this meteorite in the Harvard College cabinet presents a fine-grained groundmass, sprinkled 

 with pyrrhotite and iron. On the polished section it shows a well-marked chondritic structure. 



Specimens of this meteorite were purchased for the Whitney lithological collection of the Museum of Comparative 

 Zoology from Ward and Howell, Rochester, New York, and sections made. The sections are colored gray, with patches 

 of brownish-yellow staining from the iron. The gray groundmass contains irregular detached bits of metallic iron, 

 about which the stain extends. The groundmass is composed of crystals and grains of olivine, enstatite, pyrrhotite, 

 iron, and base. The section shows the usual chondritic structure, in which granules of olivine and enstatite are 

 cemented by the base to form the chondri. I can find no evidence either in this or in any other meteorite that I have 

 seen that they are fragmented in character, but rather evidence that the structure usually observed is the result of 

 rapid cooling upon a liquid magma of this constitution. * * * 



The base in this peridotite varies from a light to a dark ash-gray, and is fibrous granular in its structure. The 

 darker shades are generally associated with the olivine and the lighter with the enstatite. Various gradations are seen 

 between that state of the base which does not affect polarized light and that which shows feeble coloration properly 

 not a base. These gradations are owing to the differentiation in it of more or less granules of olivine or enstatite, caus- 

 ing the depolarization of the light. The feeble polarization appears to be owing to a differentiation of the base so as 

 to leave but minute portions of it in the original state, although the differences between the two states is not notice- 

 able in common light. The tendency of these granules is to unite into a homogeneous crystal, the base disappearing 

 more and more, according to the conditions attending the solidification of the mass. Furthermore, as in other rocks, 

 eo in this, the base should be expected to be one of the first materials, after the iron, to suffer alteration. The writer 

 supposes this base to be that which other writers have described as the matrix of fine dust, formed by the comminu- 

 tion of the meteoric material; flocculent, opaque, white mineral; also as feldspathic material, etc. 



A series of grains and crystals of olivine, arranged in spherical form and cemented by the fibrous-granular base, 

 forms the olivine chondri. I do not regard these as rounded forms owing their form to mechanical action, for no 

 abrupt line separates them from the surrounding material, as is the case where detached fragments are inclosed in a 

 matrix. In the same way the granules themselves show that they are products of crystallization, and not broken 

 fragments held in the matrix; everything points to crystallization in a more or less rapidly cooling body. In some 

 instances it is indeed true that an abrupt termination exists to some of the forms, but these appear to be fragments of 

 base, sometimes partly differentiated, caught in the liquid mass, instead of mechanical forms torn from some pre- 

 viously existing rock. 



This meteorite has also been described by Lasaulx, who states that it shows an evident brecciated structure, with 

 olivine grains and rounded enstatite masses, in a fine-grained groundmass, containing grains and fragments of crystals, 

 as well as iron and pyrrhotite. Plagioclase is said to be present, and the base is described as a gray, fine-grained, 

 aggregate, cementing mass, resembling the granular microfelsitic groundmass of many porphyries. 



