Oct., 1907. Meteoric Studies II — Farringtox 119 



compared with the dark-brown to black of the outer zone. These 

 microlites have an elongated form, averaging about .02 mm. in length 

 and tend to a fibrous structure. Succeeding to this inner zone, while 

 no structural change is apparent as compared with the interior of the 

 meteorite, there is a marked series of cleavage or fracture lines running 

 essentially parallel to the crust. These lines, although irregular and 

 frequently anastomosing, run at intervals of about .05 mm. The zone' 

 showing these lines has a width averaging about .2 mm. 



As regards the remainder of the section, in ordinary light a field of 

 silicate and metallic grains is presented, with the siliceous constituents 

 exceeding the metallic. There is considerable limonitic staining of 

 the silicates and the metallic grains are for the most part bordered by 

 a dark zone of the same character. Chondri of spheroidal outline oc- 

 cur here and there, but are not abundant. They are rather uniform 

 in size. Their diameters vary from .5 to 1 mm., being generally about 

 .7 mm. In structure they present chiefly the familiar ribbed and por- 

 phyritic characters produced by combinations of chrysolite and glass. 

 The general form of the chondri is spherical but many are plainly frag- 

 mental. In outline the chondri are rarely sharply separated from the 

 adjoining ground mass, althottgh this is sometimes the case. The 

 ground mass of the meteorite exclusive of the chondri is made up of 

 crystalline fragments varying from minute grains up to individuals 

 .3-. 4 mm. in diameter. Many of the larger individuals show crystal 

 outlines which are more or less rounded. High interference colors 

 and strong double refraction show these to be chrysolite for the most 

 part. The larger individuals are traversed by cleavage cracks along 

 which alteration has frequently taken place. This appears in the form 

 of brownish opaque bands which suggest iddingsite traversing the 

 fragments. Aside from these the crystals are free from clouding or 

 inclusions for the most part. One interesting crystal, however, has an 

 outer transparent portion, while the interior shows glass and skeleton 

 growths. The metallic grains consist of nickel-iron and troilite, 

 sometimes singly and sometimes in combination. They have irregu- 

 lar branching forms and seem to fill the interstices between the silicate 

 grains. Their form shows beyond a doubt that they were subsequent 

 in origin to the silicates. 



MEJILLONES. 



Through an error of the writer in copying Wulfing's classification, 

 the specimen of this meteorite in the Museum collection was desig- 

 nated * as a brecciated hexahedrite. It is in fact an iron-stone meteor- 

 * Pubs. Field Col. Mus. 1903. Geol. ser. Vol. II, p. 107. 



