The NSS Bulletin - ISSN 1090-6924
Volume 56 Number 1: 27-31 - June 1994

A publication of the National Speleological Society

Monohydrocalcite in Speleothems from Caves in the Guadalupe Mountains, New Mexico
Victor J. Polyak, Alonzo D. Jacka, and Necip Güven


Monohydrocalcite, a hydrated carbonate mineral which has been rarely documented in caves, has been found in crusts in three caves of the Guadalupe Mountains. The settings in which monohydrocalcite crusts were observed are near or adjacent to the zone of indirect light (twilight zone) of caves having large entrances with downward sloping passages. These areas are cool (<12C) and organic materials are associated with the crusts. In two caves, Gunsight and Cottonwood, monohydrocalcite, hydromagnesite, aragonite, and dolomite are constituents in crusts which have formed on inactive stalagmites in the zone of indirect light; precipitation of these minerals seems to have been from aerosols generated by collision of dripping water with the cave floor. In Hidden Cave monohydrocalcite with minor amounts of aragonite are constituents of crusts that have formed on broken stalactites lying on a silty mud floor which was moistened by small intermittent streams in a zone of complete darkness at the fringe of the twilight zone.

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