90 PERIDOTITE. 



of enstatite, olivine, enstatite and base, olivine and base, enstatite and olivine, and of base 

 and minute granules of either olivine and enstatite. 



One of the chondri is seen to possess an approximately square centre of enstatite 

 with some projecting points. Surrounding this, and also partially held in it, is the gray 

 base and semi-base, showing over much of its surface a feeble polarization, which extin- 

 guishes at the same time with the enstatite. The latter shows traces of zone building, 

 and lying parallel to the sides are other small masses of enstatite, which appear to form 

 constituent portions of the enstatite crystal. In polarized liglat, the entire chondrus 

 appears as a homogeneous enstatite, except that certain portions show mure feeble colora- 

 tion. The structure seems to me to be that of a mineral crystallizing out of a magma, the 

 processes being arrested before it was complete. Another chondrus shows a bourpiet-like 

 mass of the fibrous gray matter in the centre, surrounded in part by long masses of 

 enstatite, which hold included between and in them portions of the base. This is figured 

 in Plate II. figure 6, at the centre and on right of the central portion of the figure. The 

 lighter bars surrounding and cutting the yellowish-gray fibrous portion are enstatite, 

 which polarize conjointly as a single crystal. They contain portions of the base forming 

 the grayish parts. The central fan-shaped portion is composed of base mixed with 

 enstatite fibres and iron grains, and stained by oxide of iron. At the bottom of the 

 figure is another chondrus composed of mixed enstatite fibres and base, wliile towards 

 the left and bottom of the figure is a fissured enstatite. The rest of the figure is com- 

 posed of enstatite, olivine, and base, showing in places imperfect chondritic structure. 



In another, tlie fan-like radiation of the base with the enstatite gi'anules begins at 

 opposite ends of the chondri, meeting and interlocking towards the middle, but leaving 

 a non-differentiated oblong nebulous mass in the centre between them. The two por- 

 tions interlock in such a manner that they evidently form the same crystal mass — the 

 rudiments of a twmned crystal. 



Some chondri are composed of a rude network of biase — the meshes being filled 

 with olivine grains. This is shown in Kenngott's figure 8. One chondrus is composed 

 of an enstatite crystal surrounded by a narrow border of gray matter, apparently crowded 

 out by the crystallization of the enstatite, as is often the case in the crystallization of the 

 feldspars in modern lavas. 



Chondri are seen composed entirely of olivine grams, the lines bounding the grains 

 answering to the network of base before mentioned. One formed by an enstatite 

 mass with black ferruginous grains (magnetite) is found to continue across its apparent 

 boundary uito the adjoining enstatite, the cleavage fractures and fissures extending from 

 one to the other, both forming in common and polarized light a contuiuous enstatite 

 crystal. 



Another chondrus is composed of a sea-fan-like interior made up of base and fine 

 granules of olivine (?) surrounded by a coarser granular mass destitute of base, the entire 

 cliondrus showing in common and polarized light that it was a homogeneous mass, out of 

 which the granules have crystallized. 



In others, the base is irregulai'ly scattered through the crystals, and held as the base 

 is in minerals in recent lavas. The base in this meteorite is often completely dark 

 during the entire revolution of the stage, and every gradation exists between this state 

 and that in which it affects the polarized light considerably — nearly crystallized uito 

 the enstatite and olivine forms. \Yhile the color of the base is usually a gray, in some 

 cases it is of a brown to a black color in transmitted light. The descriptions of the 

 chondri might be greatly extended, but it would seem that enough has been given to 



