I'ALLASITK.— CUMBEKLAXDITE. 81 



containing actinolite, soipontinc, etc. ; and the question of tlie fonnation of 

 certain schistose rocks by metaniorphistn of these terrestrial palla.«sites is ;iri 

 interesting one. 



A similar structnre to that ol' this Rhode Islan I pallasite has been 

 reported in some New York and Canjida ii'on-ljearing rocks. 



Of a similar character to the Cumberland pallasite is the rock from Taberg, Sweden, 

 so long known and so well described by Messrs. Sjoren and Tornebohm.* 



The section in the collection i)urchased from Kichard Fuess of Berlin shows an 

 imperfect sponge-like mass of magnetite, holding olivine and feldspar. 



The olivine is much fissured and traversed along the fissures by serpentine and rn.i','- 

 netite bands, while in places it is entirely replaced by the secondary serpentine. 



The feldspar is in irregular, somewhat kaolinized masses, holding olivine and mag- 

 netite grains. The feldspar polarizes with a polysynthetic structure. 



A reddish-brown secondary biotite is associated with the magnetite, but is more 

 abundant than it is in the Cundjerland rock. 



For the full description of this rock the reader is referred to the original papers 

 above mentioned. This rock is figured on Plate II. figures 2 and 3. Figure 2 shows the 

 sponge-like magnetite with the inclosed olivine, while figure 3 shows a more highly 

 altered portion of the same section in which the magnetite has partly disappeared and 

 the silicates contain more ferruginous material. The reddish-brown portions are the 

 secondary mica, usually associated with or replacing the magnetite. 



The pallasites may then be described in general terms as composed of a 

 ferruginqus sponge-like or semi-sponge-like mas.s, holding olivine with or 

 without feldspar, enstatite, diallage, angite, and chromite, or spinel min- 

 erals. The sponge is formed either by native iron with pyrrhotite, or by 

 their secondary products, like magnetite. 



The alteration of these original materials gives rise to serpentine, chro- 

 mite (?), biotite, actinolite, etc. 



The general structure of the Cumberlandite from Rhode Island iv\y be 

 summed up as follows : In the least altered condition it shows a dark resi- 

 nous, crystalline, splintery and compact mass, holding porphyritically inclosed 

 feldspars, which, although characteristic of one portion of the locality, are 

 not essentiah This rock passes into a form destitute of feldspar, but having 

 the same groundmass, which contains patches of a dark-green, tine-grained 

 alteration-product, which, holds a similar relation to the groundmass as the 

 feldspar in the preceding. In the succeeding forms the resinous groundmass 



* Gcol. Foren. Forlian., 1876, iii. 42-62; 18S1, v. 610-619; 1SS2, vi. 261-267; Neucs Jalir. Miu . 

 1876, pp. 434, 435 ; 1SS2, ii. 66, 67. 



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