The country was one of the few sources of amber in the Western Hemisphere. Salt Mountain, a 16 km block of almost solid salt west of Barahona, was the world's largest known salt deposit. There were also large deposits of gypsum near Salt Mountain, making the Dominican Republic one of three sources of gypsum in the Caribbean. The country also produced hydraulic cement, limestone, marble, and sand and gravel. Substantial lignite deposits were found in the early 1980s. Deposits of copper and platinum are also found in the country.