100 PERIDOTITE. 



described. We must believe with respect to the Estherville form, that the primitive 

 mass in the condition of debris, in part stony, in part metallic, accumulated in some 

 crevice, has been subjected to metalliferous emanations, of which the product, under the 

 form of a fine network, has soldered together the components previously disconnected. 

 The spaces — so remarkable — existing sometimes between the modules of iron and their 

 rocky matrix, are artificially reproduced in the process of metallic cementation of the 

 dust of peridot, by a method which I have already described." * 



The present writer finds himself obliged to dissent from M. Meunier's views regarding 

 the origin of this meteorite, for the following reasons : He (the writer) can nowhere 

 in the sections find any evidence that its materials ever held any different relation than 

 the present, and no sign of a former fragmental state is observable to him ; but he does 

 see evidence that is convincmg to him that the entire mass has been formed by cotem- 

 poraneous crystallization, i. e., it has the same structure that a terrestrial lava of the 

 same composition, cooling under conditions that would allow the entire mass to crystal- 

 lize, would have. The inclusion of the iron in the silicates, indicating their later solidifi- 

 cation, would show that the iron was not a posterior emanation. >Such a formation as 

 M. Meunier supposes could not take place without leaving a record behind of its action. 



It has been hoped that a complete microscopic description would have been pub- 

 lished by Professor C. W. Hall, of the University of Minnesota (see Professor Peckham's 

 paper before referred to, page 98) ; but thus far he has been unable to get time for the 

 work. Professor Hall has very kindly sent me some of his sections for examination, 

 and the additional information obtained from them is given below. 



The sections sent by Professor Hall are, in theh general and mineralogical char- 

 acters, so unlike those already described, that were it not for the source from which 

 they were obtained, it would be very difficult to believe that they came from the same 

 meteorite. 



They have a confused liglit-greenish-yellow groundmass, holding irregular masses of 

 olivine, enstatite, and feldspar. The groundmass appears to be composed of olivine, 

 enstatite, feldspar, pyrrhotite, and magnetite. But little native iron is to be found in the 

 sections. The groundmass is stained a ferruginous yellow in many jdaces, and the com- 

 mencement of a serpentinous alteration was seen in some of the olivines. 



The feldspar is ui irregular glassy masses, and in imperfect crystals, showing stria- 

 tion and extinction oblique to the nicol diagonal. They contain inclusions apparently of 

 olivine, enstatite, magnetite, bubble-bearing glass cavities, etc. 



The olivine and enstatite contain also glass inclusions, magnetite, etc. The enstatite 

 in some places is dichroic along its cleavage planes, owing to its slight greenish altera- 

 tion. 



These sections, having been prepared by a student, are of such thickness, and ground 

 with so uneven a surface, that the study of them is very difficult. A few grains resem- 

 ble quartz, but they are probably unstriated glassy feldspars. My thanks are due Pro- 

 fessor Hall, and I regret that I cannot profit more by his kindness. Tliese sections are 

 so much unlUce those previously described, that I trust he will have further and thinner 

 sections made, and publish a complete description of them himself, f 



I'roin the various descriptions given it is to be concluded tliat the Estherville perido- 

 tite varies considerably in its mass, in different portions — from those parts entirely iron, 



* Comptes Rendus, 1882, xoiv. 1G59-1G61. 



f It is probable fi-oin llieii- altcruliou tliat the material from wbicli tliese sections were made had been 

 exposed to atmospheric agencies for some time. 



