No. 4.1 RESEARCHES ON METEORITES— MERRILL 3 



specks of meteoric iron, from 1 to 2 millimeters across. Troilite is also present in small rounded 

 masses of about the same size. On one broken surface was a very thin scum of black substance, 

 evidently graphite, soft enough to mark white paper; a feldspar (anorthite) was likewise 

 observed, and enstatite was also present." Further on, in discussing the analyses by L. G. 

 Eakins he remarks that " it is of course probable that the Crj O3 represents chromite, and possible 

 that the alkahcs and alimiina with a Uttle lime represent a soda-hme feldspar." Nothing is 

 said as to the presence of ohvine, though its presence is to be inferred from the 36.04 percent 

 soluble in hydrochloric acid. 



Under the microscope I find the structui-e very obscure, confused, and, as is so often 

 the case with meteorites of this class, baffling all efforts at satisfactory descriptions. Few of 

 the constituent minerals are crystallographically well developed, though occasional smaU forms 

 in the midst of the chondrules present recognizable crystal faces. The recognized constituents, 

 aside from the nickel iron and iron sulphide, are olivine and two pyroxenes, one orthorhombic 

 in crystallization and one monoclinic, the latter polysyntheticaUy twinned. The calcium 

 phosphate is cormnon in the usual interstitial forms. A black carbonaceous matter in veins 

 and coating slicken-sided surfaces is not imcommon. Nothing resembling a feldspar is to be 

 seen in any of the sections examined. (Fig. 2, PI. II.) 



GargantiUo (Tomatlan), Jalisco, Mexico. — This stone was described by Shepard,' who 

 seems to have secured 511 grams out of the total known weight of 780 grams. The mineral 

 composition as given by him was as follows: 



Per cent. 



Chrysolite 80. 00 



Chladnite (?) 10. 00 



Nickeliferous iron 7. 00 



Troilite 1 



Chromite 3.00 



Peroxide of iron J 



Total 100. 00 



Specific gravity, 3.47 to 3.48. 



He noted as a "striking peculiarity . . . the prevalence everywhere of octahedral 

 crystals of nickeliferous iron," which were "so distinct as to be recognizable with the naked 

 eye, the brilliant equilateral, triangular faces coming into view by every change of position of 

 the specimen." No chemical analysis appears to have been made, nor has it apparently been 

 studied further except by Brezina, who classes it in his catalogue - as a "kugelchenchondrit" 

 (Cc) and refers to it as having a very loose and friable grotmd mass, thick crust, large chondrules, 

 many brown flecks, Uke Sai'banovas, and the ii'on abimdant with many crystalline faces. 



A httle more may well be added to this description. The stone is so friable and the 

 abundant chondi-ules so loosely embedded that it is practicaUy impossible to get a satisfactory 

 section without sacrificing a larger amount of material than is warranted. The microscope 

 shows an indistinct and confused, fine, granular ground of olivine, enstatite, and occasional 

 grains of a monoclinic pyroxene, in addition to the metallic constituents and the sulphide. 

 (See Fig. 1, PI. III.) The fine powder treated on the slide with a drop of ammonium molj'bdate 

 yields characteristic globules and crystals of phosphomolybdate of ammonium. No feldspars, 

 even of the maskelynite type, were detected. 



A vial of fragments too small for other purposes, found in the Shepard collection, was 

 sacrificed for the purposes of analysis, with the following results: 



Per cent. 



Mineral 93. 54 



Metal 6. 46 



The metal amoxmted to 0.41 grains and consisted of: 



Per cent. 



Nickel 10. 12 



Cobalt 1. 02 



Iron (by difference) 88. 86 



> Amor. Joum. Sci., vol. 30, 1883, pp. lOi-108. > Die Moteoritensammlung, eto., 1898, p. 256. 



