COMPOSITION AND STRUCTURE OF METEORITES 



13 



angular plates of a tin white color, either Ijang parallel with the 

 taenite-kamacite plates, or in angular, jagged masses as in the 

 Tombigbee u'on (see pi. 5, fig. 3), and sometimes in dendritic forms 

 as in the iron of Arispe (see fig. 2 of the same plate). In the pallasites 

 it occurs in thin plates lying between the olivines and metallic mesh. 

 It is brittle, magnetic, and difficulty soluble in acids, but fuses readily. 

 The name rhabdite was given by Rose in 1863 to a phosphide found 

 in the Braunau, Seelasgen, and Misteca irons, occurring in the form of 

 minute prisms of the tetragonal system and commonly considered 

 identical with schreibersite. The following analyses are selected 

 from a large number available: 



I. Schreibersite from the Sao Juliao de Moreira iron. Fahrenhorst, analyst. 



II. Schreibersite from the Kendall County iron. Scher, analyst. 



III. Schreibersite from the IMagura iron. Fahrenhorst, analyst. 



IV, Schreibersite from the Cosby Creek iron. Fahrenhorst, anaylst. 



While the formula (FeNiCo)3P for this mineral is that commonly 

 accepted, a considerable list of analyses by reliable chemists could be 

 quoted from which formulas ranging from the above to (FeNiC0)4P, 

 (FeNiC0)5P, and (FeNiCo);? could be calculated. Cohen would 

 account for these discrepancies on the ground of impure or small 

 quantities of material utilized. 



The mineral has not been found in well-developed crystals. Some 

 small distorted and imperfect forms obtained by the writer from 

 the Rufi''s Mountain iron were submitted to Dr. E. T. Wherry for 

 examination, who reported as follows :^^ 



The crystals average about one-half millimeter in diameter and are irregularly 

 distorted, some of the faces being cavernous; the system of crystallization is not 

 evident on superficial examination. The faces yield, however, fairly good re- 

 flections, the positions of which can be located in many cases within 5 to 10 min- 

 utes, unquestionable tetragonal symmetry being exhibited by the angular rela- 

 tions. The forms observed are: c(OOl), a(lOO), m(llO), o(lll), x(362). In 

 addition there are rounded or poorly developed faces of other pyramids and 

 prisms. All of the form.s are incomplete, but there is hardly sufficient regularity 

 in the suppression of faces to justify the assignment of the crj'stals to any par- 

 ticular hemihedral class. 



Below are given the angles observed, which compare closely with 

 those measured on artificial crystals by Mallard, Hlawatsch, and 

 Spencer. 



51 Amer. Mineralogist, vol. 2, 1917, pp. 80-81; vol. 3, 1918, p. 184. 



