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| Formula | BaAl2Si3O10 ∙ 4H2O
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| | Optic class & sign | Biaxial negative |
| | Optical orientation | X = c, Y = b, Z = a |
| | Optical plane | (010) |
| | Relief | Low-negative to low-positive |
| | Refractive indices | nx = 1.535 -1.541
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|
ny = 1.542 -1.553
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|
nz = 1.545 -1.557
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| - |
| | Birefringence (max.) | 0.010 - 0.016 |
| | | - |
| | Optic Angle
| 2Vx
= 54 - 62° |
| | 2Vz
|
| | Sign of elongation | Length-fast, l (-) |
| | Interference figure | Broad isogyres, few isochromes |
| | Colour / pleochroism | Colourless |
| | Zoning | |
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| Form | Habit | Elongate-prismatic, with pseudotetragonal pyramids |
| | | Surface | |
| | Cleavage | 2 sets {110} |
| | Twinning | None |
| | Extinction | Straight to traces of prism faces and cleavage in prismatic sections; symmetrical to traces of {110} faces and cleavage sets in sections ⊥c |
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| Reaction textures | |
| | Alteration / decomposition | Relatively stable at surface conditions |
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| Occurence | Ign | |
| | | Met | |
| | | Sed | |
| | | Hyd | Veins in mafic volcanic rocks |
| | | Other | |
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| Distinctive properties | |
| | Additional comments | Tetragonal symmetry also occurring.
n-Δn chart: Edi – edingtonite, Gon – gonnardite, Lmt – laumontite, Mes – mesolite, Mor – mordenite, Ntr – natrolite, Sco – scolecite, Thm - thomsonite |
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