II. A. Ward — Colombian Meteorite Localities. 7 



which the etched face is divided by fine fissures. Fissures are 

 riot everywhere present, and are so fine that they may often 

 escape notice except where they are filled with schreibersite or 

 magnetite. The lamellae are short and fine, seldom exceeding 

 4 mm in length and J mm in width. The kamaeite is granular, 

 and contains etching pits which give it an oriented shimmer 

 similarly oriented throughout individual lamellae, and often 

 throughout bundles of them. Plessite is not prominent partly 

 because of its limited quantity, and partly because it is not to 

 be distinguished from the kamaeite in either color or structure. 



Great difficulty was experienced in slicing the iron. A gang 

 of eight saws, fed with emery, was kept running for 197 hours 

 to obtain seven slices ranging from 450 to 600 square centi- 

 meters in size. When it was finally laid open, the first thing 

 about the sections to attract attention was what appear in 

 section to be almost, if not quite, perfectly spherical troilite 

 nodules from 3 to 6"' m in diameter. It was not until after 

 a closer scrutiny, and after a comparison of the concretions in 

 the different slices, that they were found to be cigar-shaped, 

 rather than spherical. The lay of these is, as nearly as may be 

 determined, mutually parallel. Their direction is approxi- 

 mately perpendicular to the long axis of the meteorite, and 

 happens also to be at right angles to the plane of the slicing. 



In all, twenty-nine sections of different concretions are to be 

 counted on the five main slices. Fifteen of these are of con- 

 cretions extending through all five slices. In other words, of 

 the twenty-nine different concretions met with in five succes- 

 sive slices of less than 600 square centimeters each, fifteen at 

 least are jDarallel in position and more than 5 cm in length. 

 The evenness of distribution, length, symmetry of form, and 

 parallelism of direction, of this secreted troilite in the Santa 

 Rosa siderite is a characteristic feature which, though ap- 

 proached in some few other meteoric irons, notably LaCaille, 

 is equalled in none so far as I have observed. 



The structure of the iron has been described so completely 

 by Cohen and Brezina as to make further comment almost un- 

 necessary. Polished faces are divided more or less completely 

 by fine hair-like fissures into irregular areas 2 or 3 cm across. 

 The Assuring is everywhere present, but is not always equally 

 pronounced. A second form of hssuring is in the nature of 

 magnetite-filled cracks, sometimes as much as a millimeter wide, 

 extending inward sometimes 3 cm from the natural surface. One 

 such magnetite-filled crack passes directly through a troilite 

 concretion. 



One of the slices, which has been etched, presents a mottled 

 appearance of shimmery and dull areas, and as the angle of 

 reflection is changed the bright spots vanish and new T ones ap- 

 pear. This variable mottling is due in part to the fact that 



