Mining AI startup Terra AI closed a $20 million Series A led by Khosla Ventures and including the VC arm of mining giant BHP, CEO John Mern tells Axios Pro.Why it matters: Investors are pouring money into next-gen mining tech and domestic projects to meet surging demand for critical minerals.Zoom in: Terra AI plans to use the funds to hire, as well as develop products, for smaller mining firms known as junior miners.BHP Ventures invested $4 million in the round.The intrigue: BHP Ventures investe...