366 PROCEEDINGS OF THE NATIONAL MUSEUM. 



given by Whitfield and Smith agree much more closely than do those 

 of pecldiamite, the chief difference being in the proportional amomits 

 of iron and magnesia.^ 



It should be mentioned in this connection that the material in 

 analyses 1, 2, and 5 v/as carefully assorted and examined under the 

 microscope to assure its purity. The enstatite phase (column 2) was 

 of a bright greenish color, limpid, and alm.ost free from inciosurcs of 

 any kind. (See fig. 1, pi. 22.) The pecldiamite phase (columns 1 

 and 5) of a yellovv'-brown hue was so clouded b}^ innumerable empty 

 cavities and inclosures as to be only translucent. (See fig. 2, pi. 22.) 



Our results thus far then agree with Tschermak. I may add here, 

 however, that I can not understand the statement of Smith and others 

 relative to a mineral of an olive-green color occurring in masses of 

 from one-half to 1 inch in diameter, having an easy cleavage, espe- 

 cially in one direction, which is identified as olivine. I have made 

 repeated examinations of the mineral corresponding to this descrip- 

 tion and found it in every case to be mainly enstatite, though often 

 intergrown with small amounts of olivine. Analysis 2 on page 365 

 is of material from one of these crystals carefully freed from possible 

 admixtures with olivine by hand picking and boiling hydrochloric 

 acid and sodium carbonate solutions. 



Equally or more difficult of comprehension is his statement that 

 the solulde portion of the stone is "without a trace of lime, thus 

 indicating the absence of anorthite," I find this mineral more or 

 less abundant in every slide examined, and the solution obtained 

 by even a short digestion of the powdered stone in dilute hydi-o- 

 chloric acid yields an abundant precipitate of this constituent. It 

 is, of course, possible that working with a very small amount of 

 material (a fault altogether too common) he may have had a feld- 

 spar free sample, but an mspection of the figures on plate 23 must 

 convmce one of the insufficienc}^ of such an explanation. 



None of the writers quoted note the presence of a calcium phos- 

 phate, though the stony portion, when .powdered and treated with 

 acid ammonium moh'bdate, yields abundantly the customary 

 yellow precipitate. I have not been able to determine the mineral 

 by its optical properties alone, but when an uncovered slide is 

 treated with a di'op of the molybdate solution sundiy areas occupied 

 by an irregular and optically ijidistinct colorless mineral gradually 

 dissolve out, leaving minute cavities and yielding abundant globules 

 of ammonium phosphomolybdate. The presence of a monoclinic 

 pyroxene, the diallage of Wadsworth, is abundantly confirmed. 



1 It may be remarked that as Smith's analysis was that of the "insoluble" silicate portion and apparently 

 not examined microscopically it might naturally be expected to contain an a.<.imixture of diallage and other 

 impurities. That it does not is but one of the several puzzling things in his work. 



