56 



THOMAS STEIiRY HUNT ON A NATURAL SYSTEM IN 



condensed, having relatively high values for V. We have given, in the accompanying 

 table, No. YII, some of the more important species of this large family. Pollncite, from 

 the analysis of Eammelsberg. is a zeolite in which two-thirds of the protoxyd base is 

 oxyd of coesinm. 



§ Vl. In the same tribe of Zeolitoids we place several other hydroirs silicates, which are 

 distinguished from the zeolites by presenting different ratios between the protoxyd and 

 sesquioxyd bases. Of these the most notable species is prehnite, which, among the secre- 



VII. Tribe C. Zeolitoid. 



Spectes. 



Xanthorthite. 



Prehnite. - - 



Hamelite. - - 



Catapleiite. - 



Cancrinite. - 



Thomsonite. - 



Gismondite. - 



Natrolite. - - 



Scolecite. - - 



Mesolite. - - 



Levynite. - - 



Pollucite. - - 



Aualcite. - ■ 



Eudnopliite. - 



Laumontite. - 



Her.schelite. - 



Phillipsite. - 

 Chabazite. 

 Gmelinite. 



Faujasite. - - 



Hypostilbite ■ 



Harmotome. - 



Epistilbite. - 



Brewsterite. ■ 



Stilbite. - ■ 



Heulandite. ■ 



Edingtonite. ■ 



Sloanite. - • 



Forestite. - - 



Formula. 



(mialiSi2)Oi+2aq- (m = ce,fe) - - - 



(ca2al3si6)Oi, +laq 



(mial,si;,)oo + laq - (m= mg,fe,na) 

 (mizr2si|;)03 + 2aq -------- 



(nai;al,6si2;)05i+ 3ciCai03+4iaq - - - 

 (mial3si.i)0j + 2.1 aq - (m = caj-na" ) - - 



(caial3sii.3o)o8.5o + -lJaq 



(uaial3si6)Oio + 2aq 



(caial3si6)o,o + 3aq 



(mial3si|;)o,o + 3aq - (m = cainaj ) - - 



(caialjsicjoio + 4aq 



(ni,al3Sig)o,2 + laq - (m = csinaj) - - 



(nijalaSisJOij + 2aq - 



(naial3si8)Oi2 + 2aq - - 



(ca,al3sij)Oi2 + 4aq ------- 



(iUial3sis)Oi2+5aq - (m =iia5ki) - - - 

 (mial3Si8)Oi, + 5aq - (m = cajnaj ) - - 

 (caial3si8)Oi2 + 6aq - ------- 



(caial3si3)Oi2 ^• Caq - (m = calnaJ ) - - 

 (mialiSi9)Oi3-l-9aq - (m = na^ca?,) - - 



(caialjSiaJOij+Caq 



(mjal3Sij(,)oj4 + 5aq - (m = ba-i^ûnai',,) - 



(caial3sii2)oii; + 5aq 



(■inial3si,2)oio + 5aq - (m = srinaj) - - 



(caial3sii;)oio + 6aq 



(caial3sii2)o,5 4- 5aq ------- 



(baial4Si;)Oi2 + 4aq 



(caial3Si-)o,3 + 3aq - - 



(caia]t8i,2)o,,j + Caq - 



17-11 



18-91 



D 



2 90 

 2-95 



2-80 



2-38 

 2-26 

 2-25 

 2-40 

 2-40 

 2-lG 

 2-90 

 2-29 

 2-27 

 2.30 

 2-OG 

 2-20 

 2-19 

 2-17 

 1-92 

 2-20 

 2-45 

 2-25 

 2-45 

 2-20 

 2-20 

 2.71 

 2-44 

 2-40 



5-80 



C-75 



0-54 

 6-35 

 7-03 

 G-28 

 C-31 

 0-74 

 7-53 

 0-8G 

 0-92 

 G-38 

 7-13 

 G-GS 

 G-41 

 G-50 

 G-G4 

 G -40 

 G-77 

 G-37 

 G-54 

 G-4C 

 G -51 

 G-57 

 6-27 

 0-06 



Ckys. 



Clinorh. 

 Orthorh. 



Hexag. 



Hexag. 



Orthorh. 



Orthorh. 



Orthorh. 



Clinorh. 



Chnorh. 



Ehombo. 



Isomet. 



Isomet. 



Orthorh. 



Clinorh. 



Orthorh. 



Orthorh. 



Ehombo. 



Rhombo. 



Isomet. 



Orthorh. 



Orthorh. 



Clinorh. 



Orthorh. 



Clinorh. 



Tetrag. 



Orthorh. 



Orthorh. 



tious of basic rocks, frequently accompanies the zeolites. The species here called 

 hamelite, was described by the writer many years since as a crystalline hydrous silicate 

 of ferrous oxyd, magnesia and soda, filling the pores of a palœozoic crinoid,' while cata- 

 pleiite is a zirconic zeolitoid, in which zirconia takes the place of alumina. Here also we 

 have placed xanthorthite, a hydrous species which, by its composition and its low density, 



' Amer. Jour. Science, 1871, 1. 379. 



