Formula: Na4Al3Si9O24Cl – Ca4Al6Si6O24(CO3) Tetragonal
Description: Scapolite is a group of minerals related by complex solid solution substitutions. They are found in a wide range of metamorphic rocks formed both by regional and contact metamorphism. The minerals can resemble feldspar, and are frequently overlooked. Since the particular scapolite group mineral has generally not been determined at the reported Wisconsin localities, they are all described together below.
JACKSON COUNTY: Scapolite occurs as an accessory mineral in amphibolites found at the Jackson County Iron Mine, east of Black River Falls, SE sec. 15 T.21N. R.3W. It is associated with hastingsite, biotite, epidote, plagioclase, quartz and calcite. (Jones, 1978).
MARINETTE COUNTY: Scapolite was reported occurring at Twin Falls of the Menominee River (Lapham, 1877).
OCONTO COUNTY: Scapolite occurs with garnet, vesuvianite, clinopyroxene, hornblende and plagioclase as a contact metamorphic mineral in the Wauppee metavolcanics adjacent to the Hagar Granite near Mountain (Lahr, 1972).
ONEIDA COUNTY: Scapolite occurs in veins and matrix of intensely altered volcanic rocks in the Pelican River massive sulfide deposit in sec. 29 T.36N. R.9E. east of Rhinelander. It is found here with grossular, tremolite, diopside and calcite (Bowden, 1978).