168 Field Museum of Natural History — Geology, Vol. III. 



colored liquid has been infused into the mass and affected certain por- 

 tions. This infusion appears to have taken place subsequent to the 

 cooling of the original magma. The siliceous minerals seen under 

 the microscope are chrysolite and bronzite, apparently in about 

 equal proportions. They occur as chondri, as fragments of chondri 

 and of crystals, and as more or less completely formed crystals. The 

 chrysolite chondri tend to be of small size, circular in form and mono- 

 somatic. One such chondrus measures .45 mm. in one diameter and 

 .52 mm. in the other. Its border is composed of a series of grains 

 more or less circular in outline and .06 mm. in diameter. A series of 

 parallel alternate rods of chrysolite and glass averaging .03 mm. in 

 width fills the interior. All these and the border extinguish simul- 

 taneously. Some of the other chrysolite chondri are characterized by 

 a porphyritic structure. All the chrysolite is highly fissured, as is 

 characteristic of meteoritic chrysolite. The bronzite chondri are as a 

 rule less regular in outline than the chrysolite chondri and vary greatly 

 in size. The largest seen is nearly 3 mm. in diameter, though of 

 irregular boundary. It is made up of minute parallel fibers of bronz- 

 ite .0075 mm. in width and 2-3 mm. in length. Other chondri show 

 eccentric-radiated, parallel or irregular arrangement of fibers. One 

 conspicuous chondrus is of oval outline, 6 mm. in its longest 

 diameter and is composed of seven fan-shaped rays of bronzite set 

 in an opaque background. The rays radiate from a point near 

 the circumference of the chondrus and widen as they pass toward 

 the opposite periphery. Each ray is divided into two longitudinally 

 and there is a more or less sharply marked border of bronzite. The 

 chondrus as a whole has circular polarization. Another chondrus of 

 somewhat rectangular outline is about half composed of well-crystal- 

 lized bronzite and the remainder passes into a series of half-glassy 

 fibers. Narrow black veins evidently subsequent in origin to the 

 chondri cut through the sections. The nickel-iron occasionally exhibits 

 a tendency to follow these veins. The nickel-iron and troilite grains 

 are megascopically of amoeba-like outlines and evidently formed 

 subsequent to the chondri. The crust when seen in section on the 

 darker portions of the meteorite appears as a black, opaque band about 

 .4 mm. in width. Owing to the dark color of the interior the crust 

 is not easily distinguished from it. It is certain, however, that it 

 does not exhibit the zones usually characterizing the crust of chon- 

 dritic meteorites. As none of the sections prepared for study showed 

 crust bordering the light-colored portions, no study of this could be 

 made. 



