Thomsonite Balls Lot 501 - Specimens from IndiaTHE MINERAL THOMSONITE Thomsonite is an uncommon and desirable member of the zeolite group, forming in unique and interesting crystal aggregates. In 1997, the Zeolite Subcommittee of the IMA divided this mineral into two individual sub species, thereby regarding Thomsonite as a series of two members. The series is defined by calcium and strontium end members. Common Thomsonite, which is calcium dominating, is called Thomsonite Ca, and is usually pure