June, 1910. Meteorite Studies III — Farrington. 167 



zina as breccia-like. This term should be understood however, in the 

 same sense in which Brezina uses it, i. e., as an imitation of brecciated 

 structure, without an actual clastic origin being assumed.* The writer 

 knows of no meteorite in which this structure is so strongly marked 

 as in Leighton. Besides the spotting already referred to, the dark 

 mass of the meteorite is also speckled by numerous chondri of various 

 sizes and shapes but in general more or less circular in outline and 

 ranging from 2 mm. in diameter down. The color of these closely 

 resembles that of the light-colored spots just referred to. There 

 is also a thick sprinkling of metallic grains. These are as a rule 

 small, independent of each other and very irregular in outline. 

 Some of the larger ones are elongated, one seen being 4 mm. long 

 and 7 mm. wide. The distribution of the metallic grains as a whole 

 is comparatively uniform, except that they tend to encircle the 

 chondri. Troilite is to be seen in the form of grains, but is much 

 less abundant than nickel-iron. At one point, however, a large 

 nodule of a somewhat crescentic form occurs which has a length of 

 1 1 millimeters and a width of 5 millimeters. This troilite is of bronze- 

 yellow color, brittle, and slightly magnetic. 



The texture of the stone is firm and compact so that it breaks with 

 difficulty and takes an excellent polish. The specific gravity obtained 

 by weighing the whole stone was 3.604. 



Under the microscope, chondri appear to be much more numerous 

 in the dark-colored than in the light-colored portions of the sections. 

 This difference is doubtless in part due to the greater contrast in 

 which the chondri are thrown by the dark-colored background, but 

 there is also a real relative scarcity of chondri in the light-colored por- 

 tions. The line of demarcation between the light and dark-colored 

 portions is as sharply distinguished under the microscope as to the 

 naked eye. Leighton in this respect, therefore, forms an exception 

 to other brecciated chondrites, if Cohen's statement in regard to the 

 latter is accepted, for he states that the megascopically sharp-appear- 

 ing boundaries of the differently colored areas of such meteorites dis- 

 appear under the microscope. f Yet the difference in appearance of 

 the two portions of Leighton as seen under the microscope is not 

 sufficient to establish the existence of a true brecciated structure in 

 the sense that it is certain that the mass was at one time broken up 

 and recemented or that fragments of different origin are here seen 

 cemented together. The appearance rather suggests that a dark- 



* Jahrb. K. K. Geol. Reichsanstalt, Wien, 1885, xxxv, 172. 

 t Meteoritenkunde, Heft II. p. 63. 



