Chabazite-Mg

chabazite-Mg

saponite

aragonite

phillipsite

Images

Formula: (Mg_0.7K_0.5Na_0.1)[Al₃Si₉O₂₄].10H₂O
Tectosilicate (framework silicate), chabazite-levyne subgroup, zeolite group
Crystal system: Trigonal
Specific gravity: 1.98 measured, 1.964 calculated
Hardness: 4
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Environments

Basaltic cavities

Chabazite-Mg occurs in cavities in basalt, formed by hydrothermal alteration of feldspar and volcanic glass in a closed system with Mg-rich solutions. Associated minerals include saponite, aragonite and phillipsite (HOM).

Localities

At the type locality, the Karikás Hill quarry, Prága Hill, Bazsi, Sümeg District, Veszprém County, Hungary, chabazite-Mg occurs in basalt. It crystallises as single, colourless rhombohedra up to 0.4 mm in size. The streak is white and the lustre is strongly vitreous. In its chemical composition, a predominance of Mg is observed among the extraframework cations. However, K and Ca are also very abundant, while Na and Sr levels are very low. The ratio Si/(Si+Al) is among the highest found in chabazite of hydrothermal genesis. Associated minerals include aragonite, phillipsite subgroup minerals and saponite (AM 95.7.939-945).
Chabazite-Mg from the Karikás Hill quarry - Image

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