The Rev. S. Haughton's Notes on Mineralogy. 17 



I made a careful analysis of the whole rock and of its green 

 skeleton, with the following results. — N.B. The quantity ope- 

 rated on was 3931 grs. 



Green Calc-spar. 



Actual weight. Per cent. 



Green siliceous skeleton . . 6-54 16-63 



Alumina 029 0-73 



Carbonate of Hme . . . . 31'76 80-79 



Carbonate of magnesia . . trace 



38-59 98-15 



Spec. grav. =3-645. 



Upon fluxing the siliceous skeleton with carbonate of soda and 

 potash, I found — 



Green Siliceous Skeleton. 



Actual weight. Per-centage. 



Silica 3-57 54-59 



Alumina 0-31 4-74 



Peroxide of iron 1-66 Protoxide. 22-84 



Carbonate of lime . . . . 0-11 Lime . . 0-94 

 Pyrophosphate of magnesia . 0-90 Magnesia . 4*90 



Water&los s 11-99 



100-00 

 The mineral just described appears to me to be the Glauconite 

 of the American mineralogists, described by Dana, Rogers, and 

 others. I find its atomic proportions as follows : — 



Number of atoms. Oxygen ratio. 



Silica 1213 1213 



Alumina 91 



Protoxide of iron . . 634 ■ or»er 



Lime 33=" ^^^ 



Magnesia .... 245 



Water 1332 



From the oxygen ratio here given,'! deduce the following 

 mineralo";ical formula for this remarkable mineral : — 



3R0 



AFO^ 



3^38103 + 3 HO • (L) 



Or, Hydrated tersilicate of protoxide of iron. 



The following analysis by Rogers, of Glauconite from the 

 green grains of the greensand formation of New Jersey, will 

 serve to show the probable identity of Glauconite with the green 

 siliceous skeleton of the green calc-spar of Niigpur : — 



Phil. May. S. 4. Vol. 17. No. 111. Jan. 1859. C 



