Wannenköpfe Quarry, Ochtendung, Maifeld, Mayen-Koblenz, Rhineland-Palatinate, Germany

Na₈Al₆Si₆O₂₄Cl₂

Crystal System:cubic
Colour: colourless, white, light yellow, green, light to very dark blue, gray or pink to violet
Lustre: vitreous, greasy
Habitus: commonly as granular or compact masses. Crystals are rarer, and show typically a dodecahedron habit
Hardness: 5½ - 6
Fracture:  uneven to conchoidal
Cleavage: poor on {110}
Density: 2.31 g/cm³ 
Origin and geological occurrence: it occurs in SiO₂-undersaturated rocks (nepheline syenite, phonolite), associated with nepheline, cancrinite, leucite, and in metasomatized limestone. It can be found in cavities of ejected volcanic blocks

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Samples:

9F.13 Sodalite Blue compact aggregate #tectosilicates