Abstract
The natural occurrence of lithium in potentially economic contents is currently constrained to the following deposit types: “Hard-rock” deposits - Li - Cs – Ta (LCT) Pegmatites: Bulk 0.58 to 1.18 wt% lithium – Jadarite: Bulk average 0.84 wt% lithium “Soft-rock” deposits – Hecotire (lithium-rich clay): Bulk 0.17 to 0.24 wt% lithium – Lithium-rich tuff: Bulk average 0.30 wt% lithium Dissolved lithium deposits (brines) – Continental brine in salars: 0.01 to 0.18 wt% lithium – Geothermal brine: 0.01 to 0.03 wt% lithium – Oilfield brine: 0.01 to 0.05 wt% lithium The largest economic lithium resources and reserves in the world are currently hosted in three deposit types: LCT-pegmatites (“hard-rock”), Li-rich clays (“Soft-rock”) and continental brines (dissolved lithium).
In general terms, lithium brine deposits tend to have the lowest grades and tonnages are highly variable, with giant high-grade deposits such us Zhabuye (China, 0.100 wt% lithium) and Atacama (Chile, 0.184 wt% lithium) and the smallest and lowest-grade Clayton Valley deposit. Lithium-rich clay type deposits have medium grade and tonnage, with the largest and richest deposits represented by Thacker Pass (USA, 0.236 wt% lithium) and Sonora (Mexico, 0.229 wt% lithium). LCT-pegmatites are the highest in lithium grade, best represented by giant deposits such as Greenbushes (Australia, 1.091 wt% lithium) and Pilgangoora (Australia, 0.580 wt% lithium).
In relatively recent years, other currently economic volcanogenic deposits such as Falchani, composed of felsic lithium-rich tuffs (Peru, 0.296 wt% lithium), and Jadar, where lithium is hosted in a sodium-lithium boron silicate hydroxide named Jadarite (Serbia, 0.836 wt% lithium). LCT pegmatites have been extensively exploited given the high lithium contents in their minerals and they account for less than 40% of the known global resources. Lithium-rich continental brines account for nearly 60% of the global lithium resources. The discovery and characterization of huge lithium-clay deposits such as Thacker Pass and Sonora, as well as important improvements for lithium processing has located lithium-rich deposits as novel important lithium resources. The current predicted demand up to the year 2100 is 20 Mt lithium; world resources are currently estimated at more that 62 Mt lithium. Thus, abundant resources exist, and no long-term shortage is predicted.
SRK Speaker Session:
22th April, 11:35 - 12:20 | Technical Talk: Geology of Economic Natural Lithium Deposits
Author
Camilo de los Hoyos | Principal Geologist | SRK Argentina
