Proceedings of the United States National Museum . Fig. 21.—Datolite of secondgeneration showing moeeprismatic habit by elonga-TION ON THE a AXIS Analyses of prehnite. 1. GooseCreek. 2. Admi-ralty Inlet. 3. Theory. Si02 ... .48 .41 Trace. .06 19. 44 A1203 FezOa FeO CaO 27. 1 MgO BaO HjO+llO C H,O-110° C Total 100. 70 68 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. GG, The comparison of the above analyses indicates that the prehnit©from this locahty is ordinary in composition except in being ratherhigher than usual in ferric
Proceedings of the United States National Museum . Fig. 21.—Datolite of secondgeneration showing moeeprismatic habit by elonga-TION ON THE a AXIS Analyses of prehnite. 1. GooseCreek. 2. Admi-ralty Inlet. 3. Theory. Si02 ... .48 .41 Trace. .06 19. 44 A1203 FezOa FeO CaO 27. 1 MgO BaO HjO+llO C H,O-110° C Total 100. 70 68 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. GG, The comparison of the above analyses indicates that the prehnit©from this locahty is ordinary in composition except in being ratherhigher than usual in ferric-iron, a little higher, in fact, than the prehn-ite from Admiralty Inlet described by Johnston ^^ to which the vari-etal name ferriprehnite has been applied. That the iron is pres-ent as ferric oxide replacing alumina rather than as ferrous oxide re-placing lime was definitely determined. The optical properties of the analyzed powder were found verydifficult of determination. The confused optical structures observedin the relatively simple cr
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
