Datolite

specimen number:
2102142

location:
Roncari Quarry, East Granby, Connecticut, USA

description:
Lustrous partly gemmy colorless crystals of datolite measuring to 3.0 cm in size across the top of matrix. In good condition.

The Roncari Quarry, located in East Granby, Connecticut, is a premier locality for mineral collectors within the Holyoke Basalt of the Hartford Basin. Geologically, the site is situated in a Mesozoic rift valley where volcanic activity produced thick basalt flows containing numerous gas pockets or vesicles. These cavities were later filled by hydrothermal fluids that deposited a diverse suite of zeolite and secondary minerals, including datolite, prehnite, and babingtonite. Historically, the quarry has been a significant producer of crushed stone for construction and infrastructure in New England for several decades. While commercial aggregate extraction remains the primary activity, the site gained international fame among mineralogists for producing some of the finest datolite and prehnite specimens in the eastern United States. Access for collectors has varied over the years depending on corporate ownership and safety regulations, but the quarry remains an active industrial operation that continues to reveal new geological insights into the Triassic-Jurassic volcanic history of the region.

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