152 G. P. Merrill — Composition and structure of the 



Two pyroxenic minerals are present. The one of a gray color, 

 owing to minute cavities and dust-like enclosures, and giving in 

 all cases extinctions parallel and at right angles with the evi- 

 dent cleavage ; microchemical tests show the presence of mag- 

 nesia, but not of lime or alumina. It is hence assumed to be 

 enstatite. The second is very clear and pellucid, of a faint 

 greenish tinge, though without evident pleochroism. It 

 shows an imperfect prismatic cleavage, a pronounced parting 

 parallel to qo P ~5^, has at times somewhat fibrous or platy 

 structure, and gives extinctions on qq P -^, measured against 

 cleavage lines, running as high as 30°. Granules of this min- 

 eral isolated for microchemical tests were insoluble in hydro- 

 chloric acid. With fluorhydric acid, on a slide first covered 

 with hard balsam, they dissolved, yielding abundant rhombs of 

 magnesian fluosilicate. The solution treated with a drop of 

 dilute sulphuric acid yielded gypsum needles, and with caesium 

 chloride and sulphuric acid abundant minute, more or less 

 modified octahedra of caesium alum. The mineral is there- 

 fore assumed to be diallage, though the angle of extinction is 

 small. Olivine is quite inconspicuous, and were it not for the 

 magnesia in the soluble portion of the stone, would be quite 

 overlooked. It seems to exist, intergrown with the enstatite, 

 and cannot be isolated. The powdered rock, after being 

 passed repeatedly through a solution of sufiicient density to 

 separate the feldspar, still yields a small amount of gelatinous 

 silica, the acid solution reacting for both magnesia and lime, 

 suggesting the presence of monticellite. It is possible, how- 

 ever, that the lime may have come from inclosures of anorthite 

 too small to be recognizable. 



Repeated attempts were made at separating the two pyi^ox- 

 enes for complete analyses, but the variation in density was 

 too slight to permit of this, even when the silver-thallium 

 nitrate solution was employed. 



Inasmuch as the presence of the minerals above noted, as 

 determined microscopically, did not satisfy all the require- 

 ments of the analyses of the soluble portions, further qualita- 

 tive and microchemical tests were resorted to. It was found 

 that merely boiling the pulverized stone for a few minutes in 

 distilled water was sufficient to give a solution reacting for 

 chlorine, sulphuric acid, lime and iron. These reactions con- 

 sidered in connection with the minerals known to occur in 

 meteorites, are sufficient to suggest, if not prove, the presence 

 of gypsum, as an oxidation product of oldhamite, and of law- 

 rencite. The phosphoric acid suggests schreibersite, and the 

 odor of sulphuretted hydrogen given off by the boiling solu- 

 tion, troilite. Instead of, then, attempting to account for the 

 results of the analyses on the assumed presence of two min- 

 erals having practically the same molecular ratios, as was done 



