Beryllium was historically recovered on a small scale basis from the mineral beryl found in pegmatites until Brush Wellman (Materion) developed the Spor Mountain bertrandite deposit in Utah, as a result of which the United States dominates global beryllium supply. Emeralds are a gem form of beryl. The yearly USGS reports present beryllium production as beryl equivalent, which is 13.96% BeO of which beryllium is 36%. The beryllium content of beryl is thus 6.1%. However, the USGS assumes an average 4% beryllium content for beryl, so all the historical output figures have been converted to beryllium by multiplying the reported weight by 0.04. The annual average beryllium price is supposed to be for beryllium metal but the figures are erratic due to unclear changes in reporting for a metal that does not have a public market.