Mineral Guide > Minor Gems > Thomsonite gem stone

Thomsonite gem stone

Thomsonite gem stoneAn occurrence of this mineral, which is used ornamentally to some extent, is obtained, like chlorastrolite, in the form of water-worn pebbles weathered out of an amygdaloidal trap. The pebbles are found on the shores of Lake Superior, near Grand Marais.

Thomsonite picture