USGS Professional Paper 1802: Critical mineral resources "Today, lithium is extracted from brines that are pumped from beneath arid sedimentary basins and extracted from granitic pegmatite ores. The leading producer of lithium from brine is Chile, and the leading producer of lithium from pegmatites is Australia."
Source:https://pubs.er.usgs.gov/publication/pp1802K
update
U.S. Geological Survey National Minerals Information Center (NMIC) dated 21 december 2017