Barrerite

specimen number:
2133374

location:
Rocky Pass, Alexander Archipelago, Alaska, USA

description:
Aesthetic example for the species with the crystal lustrous and sharp measuring 2.0 cm in height coming off matrix. In great condition.

Rocky Pass is a waterway and intertidal locality situated between Kuiu and Kupreanof Islands within the Alexander Archipelago of southeastern Alaska. The local geology belongs to the Tertiary to Quaternary Kuiu-Etolin volcanic belt, characterized by a sequence of gently dipping, vesicular and amygdaloidal basalt and andesite flows that exceed 500 meters in thickness. Rocky Pass is not an industrial mining or commercial quarrying site, so it lacks formal dates of corporate operation; instead, it is a natural geological exposure. The site gained prominence in the mid to late 20th century when field geologists and mineral researchers documented its extensive zeolite-bearing cavities exposed along the tidal flats and fractured outcrops.

Barrerite is an orthorhombic tectosilicate mineral and a member of the stilbite subgroup within the zeolite group. It commonly forms flat, tabular, or lamellar crystals that range in color from white and colorless to pale pink, exhibiting a vitreous to pearly luster. The mineral features perfect cleavage, a Mohs hardness of 3 to 4, and a density of approximately 2.13. It typically occurs within cavities and fractures of deeply weathered basaltic, andesitic, or rhyolitic volcanic rocks, where it crystallizes from low-temperature hydrothermal fluid alteration.

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