PALLASITK. 69 



The Meteoric Pallasites. 



Tucson, Aruoiia. 



This meteorite is represented by two forms, known respectively as the Carleton and 

 the Ainsa meteorites. 



The Carleton pallasite is composed of (juite a compact sponge of iron, containing 

 minute rounded grains of olivine (?) Some schreibersite in black angular grains also 

 occurs.* 



The Ainsa pallasite is composed of a compact metallic sponge, the minute cells of 

 which are filled by a white siliceous mineral in rounded grains. The.se grains are arranged 

 in rude lines, giving to the iron an appearance somewhat resembling that produced by 

 iiuidal structure. From the torn and broken surface of a specimen in Professor Wliit- 

 ney's collection a number of silicate grains were removed by a needle-point, imbedded in 

 Canada balsam, covered and examined under the microscope. ^lost of the fragments 

 present the optical characters of olivine, and some contain bubble-bearing stone cavities, 

 arranged in irregular lines, the same as are the fluid cavities in quartz. A few of the 

 broken grains presented the polarization characters of non-striated meteoric feldspar, but 

 two fragments were seen whicli showed the polysynthetic twinning characteristic of pla- 

 gioclase. 



Both of the above pallasites, when sawn or polished, present a more or less compact 

 appearance, like the common siderolites, and it is only where the Ainsa meteorite has 

 been forcibly torn apart, after being partially sawn, that its true structure can be seen. 

 Since the sawn and polished surfaces of the irons are such poor guides to their structure, 

 it may be that some other irons now classed with the siderolites belong here. 



While the silicates f of the Ainsa pallasites are nominally clear and transparent, a 

 number of the fragments have been stained to a yellowish brown, owing to the oxidation 

 of the iron. 



Hemalga, Tarcqxica, Peru. 



This rock, as represented by a specimen deposited in the collections of the Boston 

 Society of Natural History, is largely composed of iron, having irregular cavities filled 

 with silicates, which are considerably decomposed in places. 



Mr. K. P. Greg states of a specimen in his possession, that its cavities were found to 

 contain pure lead, a very hard, grayish-black, semi-metallic mineral, and a yePowish- 

 brown one of an earthy texture, and insoluble in acids. Sometimes the lead only par- 

 tially filled the cavities, but at others it entirely filled them, some being large as a pea. J 



The specific gravity of this pallasite was found to be about G.oO. 



Berdjans/c, Bussia. 



According to Hiriakoff, this is composed of an iron sponge, with fine grains of olivine 

 and troilite, and on etching chows Widmannstattian figures. Specific gravity, 6.63. § 



* Whitney and Brush, Proc Cal. Acad. Sci., 1S63, iii. 30-35 ; Ilaidinger, Sitz. Wieu. Akad., 1S03. xlviii. 

 (2), 301-308. 



t Whitney, Proc. Cal. Acad. ScL, 1863, iii. 48-50. 



t Phil. Mag., 1855 (4), x. 12-14. 



§ Geol. foreu. Forhaudl., 1878, iv. 72 ; Ncues Jahr. 'Min.. 1878. pp. 653, 654. 



