Gold Occurrences in Puerto Rico

Coat of Arms of Puerto Rico

Its very name in English means Rich Port and yes there is gold in Puerto Rico.  Over seventy years before Puerto Rico became an American Possession the Spaniards established a mine on the Mami River that the first Americans found as ruins in 1898.  This old mine was discovered by W.A. Shoemaker who was traveling all over the island in behalf of the American Association of Manufacturers and the Philadelphia Commercial Museums on a commercial investigation of the island and its resources while on the outlook for possible commercial ventures.  The old goldmine on the Mami River was one of his discoveries.

Gold was discovered in the Central Highlands of Puerto Rico in the early 16^th century and there were several gold mines operating until the end of the 16^th century.  For many centuries gold mining was missing from the Island and wasn’t revived until 1828 when a mine was established once again in the Central Highlands.  

Gold was the first economy established on the island that was shipped to Spain when it was mined.  These mining ventures were built on the backs of the Taino Indians who several times revolted against their Spanish conquerors until their survivors were driven to the interior of the island where many of their women were taken as wives by the Spanish sailors finally creating the present day Puerto Ricans. 

Gold is found in five different types of deposits on the island of Puerto Rico as placer deposits, copper skarns, porphyry copper-gold deposits and acid-sulfate precious metal deposits.  It is thought by the USGS that there is plenty of opportunity to find additional deposits of gold on the island as well as in the surrounding continental shelves.  While there is no real evidence of these deposits it is possible that there are large bulk concentrations of gold in the intensively acid sulfate altered areas.  Many of the skarns are accompanying tertiery intrusives and in many of the polymetallic veins found in Puerto Rico and its offshore areas.

The first gold deposits worked by the Spaniards were probably placer gold.  These deposits can be found associated with all the major rivers on the island that drain north from the Central Highlands.  Although these deposits are mostly small it has been estimated that they may aggregate as high as 1 million ounces of gold.  There are also placer gold associated porphyry copper-gold deposits of the Utuado District where it is found in the small drainage basins of the surrounding area.

It is also thought that several underground placer deposits could be hosted in the many caves in the karst topography found on the north side of island.  Although these deposits are probably small they could also be extensive and for the most part are little explored unlike the surface rivers where there was extensive exploration under the Spaniards during the 1500s.