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To quantify the percentage of unburnt coal in beach sediments from the department of Magdalena,(Colombia) a simple procedure was devised to separate the sediment mineral phases according to their density. Sediments were collected from six beaches, at two tidal heights, in November 2012 and February 2013, before and after a spill from a coal barge that occurred on 12 January 2013. Sediments were dried, suspended in an aqueous solution of sodium polytungstate (density: 2.0 g•cm-3) and centrifuged. Because coal has a lower density (1.2-1.9 g•cm-3) than other inorganic minerals and rocks, any coal particle present in a sample concentrated in the suspended fraction, whereas more dense particles settled. To remove organic matter not corresponding to coal, the light fraction was subsequently subjected to a weak oxidation with hydrogen peroxide. To estimate an upper limit for any coal present, weight loss on ignition at 550 °C was determined for whole sediments. For the six beaches examined, the maximum weight loss on ignition was 2.4 % and the weight percentage of the light fraction (with a density 3 g•cm-3, which comprise between 10-70 % of the total sediment dry weight.  RESUMEN Con el fin de cuantificar el porcentaje de carbon mineral en playas del departamento del Magdalena, (Colombia) se llevo a cabo un procedimiento sencillo para separar el sedimento en fracciones sedimentologicas de acuerdo a su densidad. Se utilizaron sedimentos provenientes de seis playas del departamento colectadas de dos niveles mareales en noviembre de 2012 y febrero de 2013, antes y despues de un derrame de una barcaza de carbon, que ocurrio el 12 de enero de 2013. Los sedimentos fueron secados, suspendidos en una solucion de sodio politungstato (densidad: 2,0 g·cm-3) y centrifugados. Ya que el carbon tiene una densidad menor (1,2-1,9 g·cm-3) que otros minerales inorganicos, cualquier particula de carbon presente en una muestra se concentro en la fraccion ligera, mientras que las particulas mas densas se sedimentaron. Para eliminar materia organica no correspondiente a carbon mineral, se sometio la fraccion ligera despues a una oxidacion leve con peroxido de hidrogeno. Adicionalmente, para estimar un limite maximo del contenido de carbon mineral, se determino la perdida de peso de sedimentos enteros a partir de combustion a 550 °C. En las seis playas evaluadas, la perdida maxima de peso por combustion fue de 2,4 % y el porcentaje maximo de la fraccion ligera (densidad 3 g·cm-3 y que constituyen entre 10 y 70 % del peso seco total de las muestras.

QUANTIFICATION OF COAL IN THE COLOMBIAN CARIBBEAN BEACHES (DEPARTMENT OF MAGDALENA)