It's another example of the growth of Chinese investment in the US, but this time the deal is strikingly unusual: a gold retailer is acquiring an oil-and-gas producer.

Beijing-based Goldleaf Jewelry is paying $665 million for a 95 percent share of Houston, Texas-based ERG Resources.

"Goldleaf had stated that they were intending to change the company's focus more to the natural resource business and that's where we fit in," ERG Chief Financial Officer Kelly Plato told China Daily on Tuesday in an interview. "For ERG, it provides us with a source of growth capital, and I think for Goldleaf it gives them a platform in the US in oil and gas."

As for Goldleaf, the reason for the acquisition was kept short in its Feb 17 announcement: ERG Resources will help "diversify" the company from its jewelry focus.

Goldleaf is involved in the design and production process of gold jewelry products and also provides consulting services for gold investors. The company is listed on the Shenzhen Stock Exchange. Goldleaf said it will finance the deal by raising $940 million from no more than 10 investors.

Goldleaf learned that ERG Resources was trying to solicit offers for its assets and eventually agreed to the acquisition, Plato said. The deal still must be approved by US and Chinese regulators.

ERG Resources, founded in 1999, has assets in Texas and California, and is an "acquisition-oriented company", said Plato. ERG acquired assets around the Gulf Coast in 2011 and then sold them, using that money to acquire additional assets in California.

"Now that we're a little further along in that development process, we're looking at other acquisitions. We've been spending our time in the last several months looking at potential deals in and around the Gulf Coast of the US, in California near our existing operations, and trying to opportunistically find a good fit for our portfolio," he said.

Chinese investment in the US natural resources sector has surged in the recent years. According to figures compiled by New York-based research firm Rhodium Group, between 2010 and 2013, the value of investments in the energy sector more than tripled to $11.86 billion in 2013 from $3.06 billion in 2010.

"Investment in the unconventional oil and gas boom continues to be a major driver of Chinese FDI in the US, with projects worth $3.2 billion concluded in 2013 (including CNOOC's acquisition of Nexen's US operations, Sinopec's Mississippi Lime joint venture with Chesapeake, and Sinochem's stake in the Wolfcamp Shale)," said Rhodium's Thilo Hanemann and Cassie Gao in a January recap of 2013 Chinese foreign direct investment.

The US has experienced increased production in oil and gas in the last few years, and may become a net natural gas exporter by 2020, replacing Saudi Arabia as the world's biggest oil producer, according to the US Energy Information Administration.

Erica Downs, a fellow at the Brookings Institute in Washington, said there are a number of opportunities in the US available to Chinese investors that did not previously exist, especially in energy. China now spends more money on energy assets in North America than any other region in the world, based on figures from data firm Dealogic.

"For example, Exxon Mobil, Chevron, BP and BG did not participate in the recent auction for rights to develop Libra, Brazil's largest offshore oil discovery, while both CNPC and CNOOC are members of the winning consortium," Downs wrote for Brookings.

"In the absence of the US shale energy revolution, the four international companies might not have sat on the sidelines."