Hovlandite is a rare mineral from Minnesota. According to the book,
"Guide to Mineral Collections in Minnesota, Minnesota Geological Survey" 1966, "Hovlandite is a variety of zonotlite, not a true zeolite. It is often grouped with the zeolites because of it's matted fibrous appearance, and its occurrence as a secondary mineral in basic igneous rocks. Hovlandite is found as white needles, distributed throughout a green diabase containing black pyroxene crystals." The approximate measurements are 2 1/2" x 1 3/4" x 1 1/2". The hardness is 6.5 so will cut and polish well. As a fluorescent mineral is shows white, green and blue.