Datolite

Datolite is a Calcium Boron Nesosilicate and what that means is that it is a mineral that has a structure that allows for traces of other elements, like iron or copper, to be sort of mixed in.

For most of the world— I think all of the rest of the World- datolite appears as just sort of unremarkable pale crystals. But here in the Upper Midwest, environmental conditions during the Midcontinental Rift approximately 1.1 billion years ago were just right for datolite to be produced in its other form. That other form is that of finely textured porcelain-like nodules. From geologic activities in the intervening hundreds of millions of years- particularly mineral-rich waters- these nodules can and do come in every color of the rainbow and

A quick note on the colors of datolite: there simply has not been much analysis of what causes the color variations in the mineral. Much of what you will find on the topic is just speculation with no real science or analysis backing it up.

This first part of my datolite story is dedicated to Blue. What is assumed or believed to be true is that the blue color in datolite is caused by the presence of reduced copper and/or other elements trapped in the structure. Reduced copper is copper that has gained extra electrons through chemical reactions (extra negatively charged electrons reduce the element's electrical charge).

Blue is one of the rarest, if not THE rarest datolite color. I have picked out some blue datolites from different locations around the Western end of the UP of Michigan. Many of the specimens pictured here are from a famous strike of them from some 4400 feet down in the Centennial Mine in the Keweenaw Peninsula, but there are several mines where blue specimens can be found.

Please let me know if you have any questions by tagging me, Mark Jeranek, in posts to the Michigan Rockhounds Facebook Group and I can try to address them before or even in the next installment of this series.