Using the anisometricity of the crystal lattice a generalization is put forward about the habit variation of the zeolitic minerals as dependent on some salient factors such as supersaturation, temperature and A1 +Si substitution.
The fibroue zeolites natrolite, saolaite, thomsonite, and edingtonite have 2 c / ( a -+ b ) ratios 0.30, 0.36,0.51 and 0.68 respectively, that accounts for a tendency edingtonite to crystallize in short prismatic habits, natrolite invariably as aciciilar crystals. Higher supersaturations are considered favourable for tho development of longer prismatic habits, whdreas higher temperature and substitution of aluminium for silicium causo shortening of the habits. Laumontite displays a similar habit variation.
The foliatocl zcolites stilbite, epistilbite, heulandite, and brewsterite have 2 b/ (a + c) ratios 1.46, 1.85, W U , and 2.41 respectively, hence results their tendency of variation from prismatic to thin tabular along the b-axis, the first habit indicativo for higher, tho second for lower supersaturations. A1 M i substitution hcro agaiti might play a habit modifying role. The pscutloisomctric zeolites gmelinite, chabasitc, and levyne have c/a ratios 0.725, 1.086, and 1.686 I.especOively, and are in certain respects intermediate between the first two groups, here, however, the rhombohodron arid h m l pinacoitl being the two main habit forms. Once again here Al&i substitution should havo to bo considered as habit modifying factor, might be tho case as also for change of thc habit of analcime from icositetrahodron to cube. n p e i r X W a e T C f l O(iO(iUeHHe 3aK0HOMepHOCTe# B HaMeHW ยถBOCTU ra6tlTyCOB IiPA-CTilnJIOB MHtleptWIOB H 3 rpyUilU UCSJIBTOB H a OCHOBaHYIH aHH3OMeTPEi'IHOCTH