Formula: (K,Na,Ca,Sr)2-3Al3(Al,Si)2Si13O36.12H2O Monoclinic
Description: Heulandite is a member of the zeolite group usually formed under burial or low temperature metamorphic conditions in mafic igneous or sedimentary rocks.
BAYFIELD COUNTY: Heulandite is reported from amygdules in Keweenawan basalt flows exposed south of Grandview in the SE SE Sec. 36 T.45N R.6W and in the NE SE Sec. 5 T.44N R.6W (LaPoint, 1976).