Prehnite after Anhydrite with Calcite

specimen number:
2102293

location:
Lane Quarry, Westfield, Massachusetts, USA

description:
Attractive green translucent crystallized prehnite, these having replaced previous prismatic crystals of thick anhydrite, across the top of matrix with micro calcite. This is in very good condition. Choice for the locality.

The Lane Quarry, also known as the John S. Lane and Son Quarry, is located in Westfield, Hampden County, Massachusetts, and is situated within the Holyoke Basalt of the Hartford Basin. Geologically, the site consists of multiple lava flows of Jurassic-age tholeiitic basalt, which contain numerous gas vesicles or pockets where secondary minerals formed from hydrothermal fluids. The quarry is famous among mineralogists for its unique pseudomorphs, specifically green prehnite replacing anhydrite, where the prehnite has completely taken the form of the original rectangular or bladed anhydrite crystals. Historically, the site has been operated as a large-scale industrial trap rock quarry since the late 19th century, with the Lane family beginning operations around 1890. Throughout the 20th century and into the 21st, the quarry has remained a major producer of crushed stone for regional construction and infrastructure projects. While it is an active industrial site, it is celebrated in the mineralogical community for having provided some of the world's finest examples of these distinctive cast-like prehnite specimens, often occurring alongside other zeolites such as datolite and babingtonite.

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