Wednesday, August 25, 2010

⤱ Thomsonite-Ca ⤱

Thomsonite is one of the zeolite group of minerals and occurs as colourless thin prismatic crystals with a rectangular cross-section, or else as white fibrous masses or hemispheres. Its formula is NaCa2Al5Si5O20.6H2O.

This specimen is from the Waitakere Volcanics, West Auckland, North Island, New Zealand.