METEORITES OF NORTH AMERICA. 503 



Meunier 18 grouped Zacatecas as an appendix to Caillite, and made the following observa- 

 tions : 



In small specimens Zacatecas is without doubt a Caillite, the museum having a specimen which shows this very 

 neatly. But on other pieces, especially if large, one sees that the mass results from the union of numerous intimately 

 grouped elements which resemble a species of breccia. This character, certainly of great geogenic importance, would 

 perhaps justify the creation of a special type for Zacatecas, but at present we are not reduced to this extremity. 



Brezina, 19 in 1895, gave a plate showing the appearance of a section of Zacatecas. He 

 states that the troilite laths are rare and the troilite nodules irregular through union with plates 

 and lenses of the same substance. With Zacatecas he groups Barranca Blanca. 



Cohen ^ found Zacatecas capable of acquiring a weak permanent magnetism. 



Later, 21 he made a detailed study of the structure and composition of a section of the mass, 

 as follows: 



A piece weighing 92+ grams, after removing all visible troilite, was dissolved in 55 days with strong evolution 

 of hydrogen sulphide, in one part HCl+20aq. It dissolved more easily than any meteoric iron which I have hith 

 erto investigated. Action of the acid was also very uniform, the surface of the plate remaining relatively smooth, 

 instead of forming cavities in the process of solution as usual. From time to time large pieces broke away in conse- 

 quence of the coarse granular structure. The small remaining angular pieces, as usual, were very slowly attacked. 

 After removing these, also schreibersite, taenite, and little troilite nodules, there remained a not further separable 

 residue of 1.68 grams. Investigation of the latter gave the following result (I): 



The 23 per cent lacking may be ascribed to water and oxygen, which were probably taken up during the long treat- 

 ment of the piece with acid. The residue insoluble in aqua regia appeared to be chromite with transparent, colorless, 

 doubly refracting grains showing a broad border in Canada balsam. It often contained opaque inclusions. Since, 

 in addition to these, turbid, flaky particles were seen, silicates decomposable by acids may be present in small quan- 

 tity. The character of the residue of 1.68 grams is difficult to determine, owing to its high content of nickel and cop- 

 per and low content of iron. If chromium is reckoned as daubreelite and sulphur as troilite, there remains after 

 deducting CaO, MgO, and Cu, 8.96 P, 2.55 Fe, and 47.51 Ni+Co, which corresponds to an iron-nickel phosphide poor 

 in iron or an almost pure nickel phosphide. This has not hitherto been known, and is less to be expected in Zaca- 

 tecas, since the isolated schreibersite is especially poor in nickel. It may here be noted that the residue obtained by 

 Derby from Canyon Diablo, which was likewise distinguished by its high content of nickel and copper and low con- 

 tent of iron, contained much less phosphorus. Derby's result is shown above under II. Evidently, this portion of* 

 Zacatecas should be further investigated, and it would be also desirable to learn in what form the copper is present, 

 since it is very probable that in many iron meteorites there occurs an unknown copper-rich ingredient. Assuming 

 the above calculation of daubreelite and troilite to be correct, the total result of disintegration of the meteorite is as 



follows: 



Grams Per cent 



Soluble nickel-iron 87. 1426 94. 47 



Angular pieces 0. 3703 0. 40 



Taenite 0. 1554 0. 17 



Schreibersite 2. 8258 3. 06 



Troilite 0. 2356 0. 26 



Daubreelite 0. 0140 0.02 



Nickel phosphide ? 0.9948 1.08 



Carbon 0. 0312 0. 03 



Chromite and silicate grains 0.0693 0.07 



Undetermined residue rich in copper 0.4056 0.44 



92. 2446 100 



