Oct 7 (Reuters) - Here are the key ways of mining lithium, a highly reactive material that is used in batteries for electric and hybrid vehicles. Demand is likely to double over the next decade as more electric vehicles arrive on the road. ReutersLink ID='ID:nN05175007' /

Lithium is mined from three sources: lithium brines, spodumene and clay deposits.

Analysts generally agree that cost of production for lithium brines is about half that of spodumene, which is a hard rock. As a result, salt lake exploration has boomed.

BRINES

Concentration: Not all salt lakes contain lithium, and in order to be cost effective, the concentration should be 600 mg of lithium per liter.

Magnesium: Too much magnesium can also cause problems, a ratio of more than 9:1 magnesium to lithium is considered uneconomical.

Evaporation: With brines, salt water containing lithium is pumped from the ground and into an evaporation pond. Filling the pond takes about a year, then the evaporation process can take anywhere from about eight months to three years.

MAIN BRINE PRODUCERS:

SQM SQMa.SN - Atacama, Chile - over 1000 mg lithium per liter

Rockwood (ROC) - Atacama, Chile - over 1000 mg lithium per liter

Rockwood - Silver Peak, U.S. - 200 mg lithium per liter

FMC (FMC) - Hombre Muerto, Argentina - 600 mg lithium per liter

Bolivia - Salar de Uyuni - largest lithium deposit in the world

China - Zabuye, Dongtai, Xitai deposits in Tibet

SPODUMENE

With spodumene deposits, the rock must be mined, heated up to 1,100 degrees Celsius and then pulverized before the spodumene crystal are processed with acid to produce lithium.

Once a mine is in production, getting lithium from hard rock is far quicker than producing from a brine. But costs are higher because it involves traditional mining and an energy intensive separation process.

MAIN SPODUMENE PRODUCERS

Talison Lithium TLH.TO - Greenbushes, Australia

Significant deposits being explored in Canada, U.S. and China.

HECTORITE CLAY

A newer source of lithium is clay deposits - which sits between brines and hard rock in terms of cost-effectiveness.

The mining costs are cheaper with clay, as it is relatively easy to extract. But the clay must be leached or roasted to extract the lithium, a chemically intensive process.

There is currently no lithium produced from hectorite, but explorers say processing clay in Nevada could rival Chile's brines for cost-effectiveness.

CLAY EXPLORERS

Western Lithium WLC.V - Kings Valley, Nevada

Sources: Dundee Securities Corporation, Byron Capital Markets, U.S. Geological Survey, company websites. (Reporting by Julie Gordon; editing by Janet Guttsman)