Abstract
Existing information on diatomite in Costa Rica is compiled and reviewed. At present there are ten known occurrences of diatomaceous deposits, all occur in the northern half of Costa Rica, closely associated with late Tertiary (Pliocene)-Quaternary acid-intermediate volcanism. The most important known deposits are at Loma Camastro and Cañas Dulces in Guanacaste Proivince in northwestern Costa Rica where thick sequences (>50 m) of relatively pure diatomite have been reported, and provide resources estimated at over eight million metric tonnes. On this basis it tis estimated that Costa Rica has at least 10% of the diatomite reserves of Central and South America.
Little date exist the age, sedimentology and paleontology of Costa Rica diatomites. However available evidence indicates that they are of lacustrine origin. Promising avenues for research include K-Ar dating of related volcanic rocks to provide limits for the age of the diatomites, detailed studies of the role of diatomite in lacustrine sedimentation in the tropics, systematic biostratigraphical studies, and a search for evidence of Quartenary climatic fluctuation within the diatomites.
About half of the world's production of diatomite is currently used in flitration, other major uses are as funtional filler, an absorbant and mild abrasive. Future trends, incluiding the development of synthetic filters and fillers and the return to more traditional materials may cause a contraction in the overall diatomite market around the turn of the century. Hence Costa Rica should act quickly to exploit its reserves in order to maximise return on this potentially valuable export commodity.