Among rock-forming minerals, the zeolite group is large and widespread, and is enormously important to industry. Zeolites form excellent crystals. The group is structurally complex and notable for its ability to exchange cations with surrounding solutions. Numerous diagrams help visualise important structural features that define various framework types. Over 200 photographs of these beautiful minerals show each species in its geological context. After a brief introduction, the general treatment of the subject begins with an explanation of the structural chemistry and taxonomy of the group. A section on their formation and geochemistry explains the kinds of environments where zeolites are formed. Then, an entry for each mineral series provides locality information and full-colour photographs wherever possible so that collectors can see what good specimens look like and which minerals one might expect to find in association with them. An extensive bibliography is provided for readers who wish to learn more about particular topics.