Cochise College          Photos of Minerals

                          Geology Home Page

                          Roger Weller, geology instructor

                          [email protected]
                                  copyright 2004-R.Weller

Pumpellyite
Pumpellyite is also known as chlorastrolite and Isle Royale greenstone.
Pumpellyite is 6Ca.3Al₂O₃.7SiO₂.4H₂O
Pumpellyite is a hydrous calcium aluminum silicate and a member of the zeolite family of minerals.  It is closely related to thomsonite, a hydrous calcium sodium aluminum silicate.  In the following photograph, small growths of thomsonite (pink) are attached to the pumpellyite (green).  These pumpellyite nodules formed in small gas pockets (amygdules) in a basalt.  As the basalt weathered the nodules were freed from the basalt and washed up on the shores of Isle Royale in Lake Superior.  For many years these small nodules went by the name, chlorastrolite.  The largest of these nodules is about 1 centimeter.


Photo is copyright free for non-commercial educational uses. Just credit photo to R.Weller/Cochise College.