THE METEORIC PER1D(jTITJ-:.S. — SAXONITE. 87 



the writer believes, resides the cause of the peculiar structure of the chondritic meteor- 

 ites, while, if through any cause the mass cools more slowly, tlie result is to uuiUi the 

 detached grains into larger crystals, as in the Estherville meteoriUi and in the ordinary 

 terrestrial peridotites. These structures, certainly, do not vary any more from one 

 another than do the glassy, the glassy and globulitic, and the ciystalline forms of basalt. 



The base in this peridotite varies from a light to a dark ash-gray, and is fibroas-gran- 

 ular in its structure. The darker shades are generally associated with tlie olivine and 

 the lighter with the enstatite. Various gradations are seen between that state of tlie 

 base which does not affect polarized light, and that which shows feeble coloration — 

 properly not a base. These gradations are ownig to the diflerentiation in it of more or 

 less granules of olivine or enstatite, causing the depolarization of the light. The feeble 

 polarization appears to be owing to a diflerentiation of the base so as to leave but mi- 

 nute portions of it in the original state, althougli the difference between the two states is 

 not noticeable in common light. The tendency of these granules is to unite into a homo- 

 geneous crystal, the base disappearing more and more, according to the conditions attend- 

 ing the solidification of the mass. Furthermore, as in other rocks, so 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 comminution of the meteoric material, — flocculen*;, 

 opaque, white mineral ; * also as felspathic material, etc. 



A series of grains and crystals of olivine, arranged in spherical form and cemented 

 by the fihroHS-fjranular base, forms the olivine chondri. I do not regard these as rounded 

 forms, owing their shape to mechanical action, for no abrupt line separates them from 

 the surrounding material, as is the case when detached fragments are inclosed in a 

 matrix. In the same way the granules themselves show that they are products of crys- 

 tallization, and not broken fragments held in the matrix. As said before, I can see no 

 structure, in this or in any of the other meteorites examined, supporting the mechanical 

 theory of their origin; but everything observed, in my judgment, points to crj'stalliza- 

 tion in a more or less rapidly cooling body. In some instances it is, indeed, true that an 

 abrupt termmation 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 previously existing rock. 



This meteorite has also been described by Lasaulx, who states that it shows an evi- 

 dent 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, tine- 

 grained, aggregate, cementing mass, resembling the granular microfelsitic groundmass 

 of many porphyries.f 



Figure 4, Plate II., shows well the finer-grained portions of this meteorite with 

 the native iron. The portion to the left of the centre represents one of the chondri, 

 composed of detached grains held in a dark base. The grains are found to be divided by 

 polarized light into three sets, one of which occupies the lower portion and the other two 

 the upper portion of the chondrus. The grains in each division act optically as a unit, 

 and cause the chondrus to present the appearance of a crystal composed of three 

 twinned portions ; and it is here thought that had not the crystallization been arrested, 



* Maskolvne, riiil. Majr , 1S68 (-1), xxvi. 1:^8. 

 t Sitz. niedcr. Gcsclls. Bonn, 1SS2, pp. 102-105. 



