SalAmmoniac

specimen number:
2282103

location:
Paricutin Volcano, Uruapan, Michoacan, Mexico

description:
A crystallized grouping of salammoniac.

The Paricutin Volcano, located near Uruapan in Michoacan, Mexico, is a famous monogenetic cinder cone that provided scientists with a complete record of a volcano birth, growth, and death. Geologically, the volcano is part of the Michoacan-Guanajuato volcanic field within the Trans-Mexican Volcanic Belt, characterized by calc-alkaline basaltic andesite and andesite lavas erupted through continental crust. Activity began abruptly in a cornfield on February 20, 1943, generating intense strombolian eruptions, extensive ash falls, and heavy lava flows that eventually covered the nearby villages of Paricutin and San Juan Parangaricutiro. The eruptive phase involved continuous venting of volcanic gases and regular effusions of lava, building a 424-meter-high cone. Primary eruptive activity ceased completely in March 1952, and while the site was never an active industrial mine or quarry, the cooled lava fields and active fumaroles served as temporary collecting localities for specialized high-temperature sublimate minerals.

Sal ammoniac is a rare ammonium chloride mineral that typically forms as a volcanic sublimate around active fumaroles and burning coal seams. Geologically, the mineral precipitates directly from hot gas phases when volatile, nitrogen-rich volcanic vapors cool upon contact with the atmosphere, forming delicate skeletal crystals, crusts, and encrustations. It is highly soluble in water and is historically notable as a distinct mineral species derived from volcanic outgassing environments.

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