Blockchain technology company Blockstream Mining said on Saturday that Square Inc (SQ.N) will invest $5 million to build an open-source, solar-powered bitcoin mining facility at one of Blockstream"s U.S. sites. Blockstream, in an announcement on its blog, said the "facility will be a proof-of-concept for a 100% renewable energy Bitcoin mine at scale." Square, in a tweet, said it was teaming up with Blockstream as part of its Bitcoin Clean Energy Initiative.