70 THE SIDEROLITES AND PALLASITES. 



Decsa, Chili 



This is composed of a compact iron sponge, containing inclosed silicates. Dr. S. 

 Meuuier detected in it troilite, schreibersite, graphite, olivine, hypersthene, pyro.Kene, 

 enstatite, chromite, etc. Specific gravity varies from 6.10 to 6.24, but no satisfactory 

 analysis exists of it as a whole.* 



Atacama, Bolivia. 



The rock found in the Desert of Atacama, Bolivia, is described as a cellular or spongy, 

 metallic mass ; the cells filled with granular, greenish-white olivine. The cellular spaces 

 instead of being rounded, as in the other rocks of this species, are stated to be angular. 

 An analysis of this rock as a whole is much to be desired, although a rough approxima- 

 tion is given in the list of analyses. A correct chemical analysis would probably sliow 

 this to be more basic than the Pallas rock of Siberia.f 



A specimen in the Harvard College Mineralogical Cabinet is proliably from the same 

 pallasite. This shows a very coarse sponge of iron, holding angular and rounded grains 

 of olivine. The olivine is yellowish-green in color — the yellowish tint owing in part to 

 a ferruginous staining. The coarseness of the iron sponge allies this more nearly than 

 any of the other pallasites seen, except that from Tarapaca, to the siderolites. 



On one side it shows a surface closely resemblbig an ordinary slickenside, but on 

 another side is to be seen the remains of a fused crust — the common mark of a meteor- 

 ite. Some pyrrhotite was seen in this rock. 



Figure 1, Plate I., is from a tracing made from the polished surface of this specimen. 

 Owing to the dulness of the polished face — the polishing having been done many years 

 ago — it was impracticable to get the outlines exact. The general structure is well 

 shown for the spongy metallic iron, but the olivine grains are far more angular, as a rule, 

 than the figure represents them to be. 



Specimens of an Atacama meteoric iron in the jMineralogical Cabinet, received from 

 Professor I. Domeyko, show that this formed a metallic sponge holding olivina Only 

 traces of the olivine are left, and Ijeyond it nothing can be told regarding the silicates 

 that might have been contained in this sponge. Some pyrrhotite was seen. This con- 

 tains less iron probably than the Pallas iron. 



xinother specimen of Atacama iron in the same Cabinet, received from a IMr. Clay, of 

 Philadelphia, is similar to that figured (PI. I. fig. 1), but the sponge is not so coarse, 

 and the olivine is more abundant. This mineral is considerably decomposed, and the 

 iron much oxidized. 



Bilhurg, Prussia. 



A coarse sponge of iron, containing in its cells light-greeni.sh-brown olivine. The 

 only specimen seen by the \vi-iter somewhat resembles the Atacama meteorite, but, per- 

 haps, contains even more iron. 



* Dauln-ee, Comptes Rendus, ISGS, Ixvi. 571, 572 ; Meuuier, Cosmos, 1869 (3), v. 552-556, 579-5S6, 

 612-619. 



t Traus. Roy. See. Ediu. 1831, xi. 223-228 ; Clark, Metallic Mclcoriles, 1851, pp. 17-19. 



