Photomicrograph showing tiny high-relief grains of svanbergite (“aps,” which stands for "aluminum phosphate mineral") in a pyrophyllite matrix with hematite (“hem”) and rutile (“rt”). The sample is a thin-section of
metapelite from the Baraboo Quartzite, near Baraboo, Wisconsin. (Photo by Gordon Medaris.)

Formula: SrAl3(PO4)(SO4)(OH)6 Hexagonal


Svanbergite forms as a result of medium-grade metamorphism of aluminium-rich sediments..

SAUK COUNTY: Microscopic grains of svanbergite occur in metapelite layers within the Baraboo Quartzite where it is associated with pyrophyllite, quartz, hematite, and rutile. Grains are “equant and have diameters of 10-20 microns.” The svanbergite ranges from nearly pure svanbergite to a composition approaching goyazite (Medaris and Fournelle, 1998).