Barrerite

specimen number:
2282065

location:
Rocky Pass, Alexander Archipelago, Alaska, USA

description:
Choice lustrous crystals measuring to 3.0 cm in height coming off matrix. In great condition, very fine for the species.

The Rocky Pass locality, situated within the Keku Strait between Kuiu and Kupreanof Islands in the Alexander Archipelago of southeastern Alaska, is a prominent mineral collecting site rather than a commercial industrial mining or quarrying operation. Geologically, the area is part of the Tertiary Kuiu-Etolin volcanic plutonic belt, characterized by an extensive sequence of gently dipping extrusive basalt flows, mafic tuffs, and volcanic flow breccias. The mineralization occurs within vesicles and gas cavities in the basaltic host rocks, which were filled by low-temperature hydrothermal solutions rich in sodium and silica. While no large-scale corporate mining ever occurred here, the locality gained widespread recognition among mineralogists and field collectors in the late twentieth century after exceptional mineral pockets were discovered in the intertidal zone, where specimens are traditionally hand-extracted below the high-water line during low tides.

Barrerite is a sodium-dominant member of the zeolite group that forms as a secondary mineral within the gas cavities of altered volcanic rocks. Geologically, it crystallizes from late-stage, sodium-rich fluids that interact with basaltic or andesitic matrices under low-temperature hydrothermal conditions. The mineral typically manifests as transparent to translucent, colorless, white, or pale pinkish-bladed crystals that exhibit a vitreous to pearly luster and a distinct orthorhombic symmetry. It commonly occurs as thin, tabular plates, radiating crystal clusters, or fragile intergrown aggregates, frequently sitting on top of a drusy quartz or chalcedony lining within the protective hollows of its volcanic host.

Questions about this specimen?
Send an email or call us: 314-341-1811.