Journal of Cave and Karst Studies - ISSN 0146-9517
Volume 60 Number 2: 121-125 - August 1998

A publication of the National Speleological Society

History of the Guano Mining Industry, Isla de Mona, Puerto Rico
Edward F. Frank


Isla de Mona, Puerto Rico is ringed by hundreds of flank margin caves (Frank 1993; Mylroie et al. 1995). In the late 1800s and early 1900s, ~150,000 metric tons of phosphorite, altered bat guano, were mined from the caves. A high phosphate content made the phosphorite a valuable fertilizer (Wadsworth 1973). Briggs (1974) indicates the guano deposits have been exhausted from seven of the eight largest known cave systems on the island. Many relics from the guano mining days are still present in the caves and surrounding areas today.

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