Until 1948, most of the world's rare earths came from sand deposits in India and Brazil. Through the 1950s, South Africa mined most of the world's rare earths. This happened after large veins of a rare earth bearing mineral were found there. Through the 1960s until the 1980s, a mine in California was the leading producer. Today, the Indian and South African deposits still make some rare earth concentrates, but they are very small compared to the amount being produced in China. China had produced over 95% of the world's rare earth supply. Most of this has been done in Inner Mongolia, even though it had only 37% of proven reserves. Although these numbers have since been said to have lowered to 90% of global production and a proven reserve rate of only 23% by 2012. All of the world's heavy rare earths (such as dysprosium) come from Chinese rare earth sources such as the polymetallic Bayan Obo deposit. In 2010, the United States Geological Survey (USGS) released a study which found that the United States had 13 million metric tons of rare earth elements.