NO. 2341. THE ESTHERVILLE, IOWA, METEORITE— MERRILL. 



366 



pocket lens, or even in many cases with the unaided eye, shows the 

 mineral in two distinct phases — 1, a green, highly lustrous form in 

 crystals up to 50 mm. in length, with very evident cleavage, some- 

 times showing a greasy or opalescent luster; 2, the yellow-brown 

 or opalescent phase without crystal form but very evident cleavage, 

 forming the peckhamite of Smith. This last occurs sometimes in 

 globular and pebblelike forms which show up on a broken surface 

 in a manner suggestive of the perlitic structure of some rhyolitic 

 glasses and again in partially filled cavities, sometimes forming a 

 coating on the interior wall not more than a millimeter or so in thick- 

 ness, presenting on the inner surface a botryoidal structure such as 

 is common to minerals deposited from solution, as silica, or limonite 

 in geodic form. The two phases, though often in close juxtaposi- 

 tion, are so widely variant that separations and analyses of each were 

 undertaken, with the results given below. 



Not being satisfied to let pass the apparent lack of agreement in the 

 peckhamite analyses by Whitefield (column 1) and Smith (column 3), a 

 second sample v^as taken from a pebble-form inclosure some 2 centime- 

 ters in diameter in the large mass of this meteorite in the Yale Univer- 

 sity collections. This yielded Mr. E. V. Shannon, of the Department of 

 Geology in the United States National Museum, the results in colum,n 

 5. It will be noted that this last differs from ^Vliitfield's analysis in 

 showing an increase of 1.50 per cent silica (SiOj) and 2.61 per cent 

 magnesia (MgO) and a decrease of 2.15 per cent ferrous oxide (FeO). 

 Also^in carrying a small amount of lime. Inasmuch as I have no 

 reason to doubt the accuracy of either of these analyses, I am led to 

 the conclusion that the mineral, itself an alteration product, is some- 

 what variable. I confess, however, to having diflficulty in accept- 

 ing Smith's results (column 3) on the same terms. It is to be noted 

 incidentally that both Whitfield's and Shannon's agree fairly well 

 with those of the enstatites of the Lodhran and Ibbenbuhren meteor- 

 ites as given by other workers. The two analyses of enstatite as 



