The estimated value of nonfuel mineral commodities produced in Puerto Rico was $84.8 million in 1995, excluding the value of crushed stone, which accounts for approximately 30% of the commonwealth's mineral value and is the island's 2nd leading mineral commodity. In 1995, 10.9 million metric tons of crushed stone were produced, for a value of $80.8 million. Even with crushed stone being excluded, Puerto Rico's mineral value was greater than that of seven mainland states. Cement is the most valuable mineral commodity produced. Lime ($3,650,000) and clay ($370,000) production in 1995 posted changes of 23% and 9.4%, respectively, from the values reported in 1994.
A multiyear study of the island's known and undiscovered mineral resources indicated that at least 11 different types of metallic mineral deposits, including copper, iron, gold, manganese, silver, molybdenum, zinc, lead, and other minerals, occur on the island in additon to the industrial minerals (cement, stone, clay, and sand and gravel) currently being produced.
Approximately 1,500 people were employed in mining in 2002. Mining is currently limited to quarry operations.