72 THE SIDEKOLITES AXD PALLASITES. 



A specimen in the Harvard Mineralogical Cabinet shows the same characters as those 

 given in the various papers relating to tliis iron, mchiding even the parallel minute tubes 

 in the olivine ; hence this specimen is doubtless authentic. A tracing of the polished 

 surface of this specimen is given in figure 2, Plate I. Of course, from the method em- 

 ployed, the most that could be done was to show the relation of the iron to the olivine ; 

 for the pyrrliotite could not be separated from the metalhc iron in making the tracing. 

 Tliis apparently has less iron than the Atacama pallasite. 



A figure of a polished surface of the Pallas iron has been given by Dr. Carl V. 

 Schreibers, which seems to be very good, except that the olivine lias been too highly 

 colored.* 



Potosi, Bolivia. 



Of a similar character is the Potosi rock, described in 1839 as a meteoric iron, 

 " cavernous, filled with vacuities, most of which are irregular, but some have the form 

 of a rhombic dodecahedron ; some of them also are filled with a greenish vitreous sub- 

 stance, similar to the olivine of Pallas." f 



Brcdiin, liusaia. 



This is said to contain somewhat less iron and more olivine than the Pallas rock, but 

 otherwise to be of similar composition and structure. 



Rittersgrim, Saxony. 



The Eittersgriin pallasite was regarded by Weisbach as composed of 30 per cent of 

 nickeliferous iron, and 70 per cent of an unmetallic brown mass. Tlie latter was said 

 by Winkler to be composed of bronzite (enstatite) pyrrliotite, schreibersite, with asmanite 

 [tridymite]. 



Breithaupt had held that the silicate was olivine.^ 



In Fouque and Levy's Mineralogie ]\Iicrographique (PI. LV. fig. 2) is given a 

 microscopic section of the Eittersgriin rock which shows that it is composed of iron, 

 diallage, olivuie, and angite. The olivine contains octahedrons and grains of pleonaste. 

 The structure is much like that of the pallasite from Cumberland, Ehode Island 

 (Cumberlandito). 



A specimen in the Harvard College Mineral Cabinet has been figured from the 

 polished surfaces. In this, while the iron in places forms a coarse sponge, in other parts 

 it is much less in amount and occurs in detached irregular grains. Considerable pyrrlio- 

 tite is found in this, forming part of the sponge or in irregular grains, and in figuring 

 (PI. I. figs. 3, 4) has not been separated therefrom, since the design has been simply to 

 show the general structure. The iron where etched shows the usual Widmannstiittian 

 figures. The silicates cannot, of course, be separated through the examination of a 

 polished surface, except partially. However, this specimen appears to contain consider- 

 able well marked ohvine. 



* Stein-und Melall-Massen, 1820, Plate VIII. page 70. 



t Pliil. Mag., 1839 (3), xiv. 394; Cbrouique Scientiflque, 1839, i. 31; Aim. Physik Cbemie, xlvii. 470; 

 Neues Jahr. Miii., 1840, p. 229. 



} Nova Acta Leop. Acad. Halle, 1878, xl. 333-3S3; Berg. Hiitt. Zeit..,1862, pp. 321, 322. 



