A Gold mining company that has been widely credited for its pioneering technology for using molten salt to extract gold from the Earth has bought US ETFs for $15 billion.

Goldman Sachs, the world’s largest investment bank, on Tuesday announced a $15.4 billion, two-year investment in the New York-based Gemini Minerals ETF, the second such deal in the past 12 months.

Gemini’s US subsidiary, Gemini Resources, is also expected to purchase a second ETF, known as GRAIN, that tracks global gold prices. 

Geminis shares rose 6.5% to $26.96 in afternoon trading.