Prehnite is a very common mineral that seldom forms large, beautiful crystals. These unique pastel blue crystals, to 1 inch in size, came out of a single pocket in the Merelani tanzanite mine in the summer of 2013. These are unique especially for the color, for crystallized prehnite. In size and sharpness of form, particularly on some of the rosettes shown here, they are among the best of species from any locality, and we believe they surpass the rare crystals from the Jeffrey Mine in Quebec (which have gray to pale green color). Specimens from this pocket are now in the holdings of the Smithsonian and other major museums.