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| Formula | (Sr,Ba,Ca)2Al4Si12O32 ∙ 10H2O |
| | Optic class & sign | Biaxial positive |
| | Optical orientation | X near c, Y near a, Z = b |
| | Optical plane | Optic plane ⊥ (010) |
| | Relief | Low-negative |
| | Refractive indices | nx = 1.510 -1.513
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ny = 1.512 -1.517
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nz = 1.523 -1.527
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| | Birefringence (max.) | 0.013 - 0.014 |
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| | Optic Angle
| 2Vx
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| | 2Vz
= 47 - 65° |
| | Sign of elongation | Length-slow, l (+), and length-fast, l (-), in elongate sections sub-∥ a as Y is close to the long axis of the crystals |
| | Interference figure | |
| | Colour / pleochroism | Colourless |
| | Zoning | - |
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| Form | Habit | Granular, elongate-prismatic |
| | | Surface | |
| | Cleavage | {010} |
| | Twinning | {010} lamellar |
| | Extinction | Inclined to traces of prism faces, {100} faces and {010} cleavage |
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| Reaction textures | |
| | Alteration / decomposition | |
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| Occurence | Ign | |
| | | Met | |
| | | Sed | |
| | | Hyd | Veins, cavities and fractures of basaltic rocks, trachyte, aplite, syenite, schists |
| | | Other | |
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| Distinctive properties | Relatively rare zeolite; low negative relief, upper first-order interference colours, large extinction angles in sections subparallel to {010} |
| | Additional comments | n-Δn charts A, B: Bre - brewsterite, Cpt - clinoptilolite, Epi - epistilbite, Hul - heulandite,
Lev - levyne, Stb - stilbite, Yug - yugawaralite |
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