THOMSONITE NaCa5Al5O20.6H2O Orthorhombic

Description: Thomsonite is a member of the zeolite group often found in radiating clusters of varying color in the amygdules of volcanic rocks.

Iron County: Thomsonite occurs abundantly in outcrops of the Porcupine volcanics along the Montreal river below the dam along Saxon flowage. The thomsonite occurs as coarse radiating bladed crystals in cavities and veins associated with lava flow tops. (Cannon, 1996).

Return to Wisconsin Mineral List