(Reuters) - Africa, Australia and Canada likely hold the key to a geopolitical battle being fought to end China's stranglehold over obscure elements used to build high-tech items from headphones to missiles.

The three are the most likely home to vast reserves of rare earth elements. The commodities are almost exclusively produced by China, which unnerved global powers last year by threatening to restrict exports to help it settle political scores.

While all three have promise, Africa may offer the most potential, with geologists saying it has more than half the world's deposits of carbonatites, a type of rock formation seen as prime hunting ground for rare earths.

"That immediately makes Africa a destination of choice if you want to find rare earth elements in carbonatites," said Paul Nex, senior geologist at Umbono Capital.

Another advantage Africa offers is vast amounts of monazite sands left over from other mining operations on the continent from which rare earths can be extracted, experts said.

Carbonatite deposits are found in most African countries, according to geological surveys, with investment likely going to states with little red tape, infrastructure to take ore to ports and deposits large enough to make ventures profitable.

The Great Western Minerals Group's Steenkampskraal project in South Africa has some of the highest concentrations of certain types of rare earths of any mine outside of China.

Rare earth -- not as rare as their name suggest -- are some of the world's most obscure elements used in some of the world's most familiar devices including cell phones, flat screen TVs and microwave ovens.

The hunt for rare earths hit a high point at the end of last year when China, which produces about 95 percent of them, made its threat, prompting South Korea to set aside about $1.4 billion in 2011 for supplies and Japan about $650 million.

As prices for the elements started to rise, so did the interest in reviving mines outside of China that closed years ago when they no longer were cost-effective to run.

"Everybody started looking for these rare earths at about the same time. There is really not a lot of difference between certain African countries and Australia or Canada," said Judith Kinnaird, professor of economic geology at the University of Witwatersrand in Johannesburg.

"Anyone who can bring something together in three to five years is going to be at a great advantage," Kinnaird said.

DIGGING IN AFRICA

Rare earth stocks were the darlings of 2010. Now investors are casting a discerning eye over the sector, betting that only a handful of companies will survive the race to supply the world with the high-tech metals of the future.

For now, the main hunting grounds are a handful of the revived mines in Australia, Canada, South Africa and the United States where rare earths were extracted before China jumped into the field and priced them out of the market.