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| Formula | (Na,Ca0.5,K)4(Al4Si8)O24 • 11H2O |
| | Optic class & sign | Uniaxial positive or negative |
| | Relief | Moderate-negative |
| | Refractive indices | no = 1.476 -1.494
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ne = 1.474 -1.480
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| n increases with increasing Ca and Sr content |
| | Birefringence (max.) | 0.002 - 0.014 |
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| | Sign of elongation | |
| | Interference figure | Indistinct due to low birefringence |
| | Colour / pleochroism | Colourless |
| | Zoning | - |
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| Form | Habit | Dipyramidal crystals with minor prism faces, equigranular, radiating aggregates |
| | | Surface | Commonly euhdral to subhedral |
| | Cleavage | {1010}; parting on {0001} |
| | Twinning | On {1010), uncommon |
| | Extinction | Symmetrical to pyramid faces and straight to basal and prism faces in sections parallel c |
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| Reaction textures | |
| | Alteration / decomposition | |
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| Occurence | Ign | |
| | | Met | |
| | | Sed | |
| | | Hyd | Vesicle and fracture fillings in basaltic rocks, hydrothermal veins, precipitates in pegmatites |
| | | Other | |
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| Distinctive properties | Distinct habit if euhedral; uncommon zeolite
Note: Reliable identification of zeolite species may require chemical analysis, X-ray diffraction, and/or DTA |
| | Additional comments | n-Δn chart: Anl – analcime, Cbz – chabazite, Fau – faujasite, Gis - gismondine,
Gme – gmelinite, Hrm – harmotome, Php – phillipsite, Wrk - wairakite |
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