Stilbite. From the Bureau of Mines, Mineral Specimens C\01733, courtesy of the U.S. Geological Survey Denver Library Photographic Collection.

Formula: NaCa4[Al9Si27O72].nH2O Monoclinic


Stilbite is a member of the zeolite family. It often forms vein and amygdule fillings in basaltic igneous rocks.

ASHLAND COUNTY: Brownish plates of stilbite about 1 cm. in diameter are found in thin veins with calcite cutting the lava flows under the footbridge across the Bad River gorge in Copper Falls State Park (SE sec. 17 T.45N. R.2W.) (Spiroff, 1952).