Dachiardite-Na, Ferrierite-Na

This specimen's surface is coated with a 60/40 mix of white radial sprays of acicular dachiardite and clear, glassy, colourless, well-formed orthorhombic ferrierite-Na (distinct from the more common monoclinic form of ferrierite-Na). Dachiardite is a rare silica-rich zeolite belonging to the mordenite group and was first described in 1906 by D'Achiardi from a pegmatite dyke (Filone della Speranza) in San Piero, Elba, Italy. This particular sample was found in vesicular Miocene basalt breccia within Columbia River Dike boulders, west of Altoona, Wahkiakum County, Washington, showcasing a unique and rare mineralogical assemblage that looks stunning under the microscope.