RE:Link to the article which Elon Musk tweeted about ... There was a follow-up artcle in CleanTechnica on Aug 23 which has not been mentioned here. It discusses lithium extraction, notes that Elon Musk has attempted to acquire a brine type lithium extraction company in the past, and includes new words from SLL CEO Robert Mintak " we are more of a technology company ".
see the complete article at https://cleantechnica.com/2020/08/23/digging-into-less-conventional-lithium-mining-options/
As to what is driving the price and volume surge, I can only speculate. SLL has land staked in Arkansas, as well as California, not too far from a Tesla plant)) And we know Elon likes the technology, and can buy the company with his lunch money. Hmmm...