Loughlinite with Searlesite

specimen number:
2133257

location:
Westvaco Mine, Sweetwater Co., Wyoming, USA

description:
Crystalline loughlinite and searlesite with minor matrix. Nice example for both species.

The Westvaco Mine, located in the Green River Basin of Sweetwater County, Wyoming, is a major underground operation focused on extracting trona from the worlds largest known sodium carbonate deposit. Geologically, these vast trona beds formed during the Eocene Epoch within the Wilkins Peak Member of the Green River Formation, a result of the evaporation of the prehistoric Lake Gosiute. The mine is the type locality for loughlinite, a rare sodium-magnesium silicate that appears as silky, asbestos-like fibrous masses often associated with shale. Additionally, the site produces exceptional specimens of searlesite, a sodium borosilicate mineral that typically forms as distinct prismatic crystals or radiating clusters within the saline sedimentary layers. Historically, the Westvaco Mine was the first shaft mine in the district, opened by the Westvaco Chlorine Products Corporation in 1947 to exploit the high-purity trona. Now operated by Genesis Alkali, the facility has been in continuous production for over seventy-five years, serving as a critical industrial source for soda ash while remaining a significant scientific site for the study of rare authigenic evaporite minerals.

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