Bright white porcellaneous datolite mass in dark green chlorite in gabbro. From Buckley Quarry, Douglas County, Wisconsin. Field of view is about 1 cm. left to right. (Photo by W. Cordua.)

Formula: Ca(HBSiO5) Monoclinic


Datolite is a low temperature hydrothermal mineral found in cavities and veins, especially in basalts and gabbros.

DOUGLAS COUNTY: White fine-grained granular aggregates of datolite, reminiscent of those from Michigan’s Keweenaw Peninsula, occur on prehnite in veins cutting gabbro in the Buckley Quarry near Amnicon Falls (NW Sec. 32 T.48N R.12W) (Cordua, 1991).