Okenite, Gyrolite and Heulandite
CHEMISTRY Ca5Si19O23H2O
CRYSTALLOGRAPHY Triclinic
CRYSTAL GROWTH AND HABITS Typically forms as fibrous balls with crystals in radiating growths; also as bladed crystals
COLOR AND OTHER OPTICAL PROPERTIES Transparent to translucent; most commonly white to slightly yellowish.
HARDNESS 4.5 - 5
SPECIFIC GRAVITY 2.3
LUSTER Vitreous to pearly
STREAK White
BREAKABILITY Perfect basal cleavage; fibrous crystals are somewhat elastic.
OCCURRENCE Most commonly found in voids or pockets in basalt.
ASSOCIATED MINERALS Zeolites, calcite, apophyllite, prenite, quartz
MINERAL NAME Named after the German naturalist Lorenz Ocken