Ann: June 2017 Quarterly Activities Report, page-39

They are doing it so they can work out an executable mining plan and product streams i.e. Spodumene Concentrate and Petalite Concentrate. Petalite Concentrates will need a separate flotation circuit (at some stage down the track) and generally produces a lower grade (~4%) concentrate by my read of things. Petalite converts to beta-Spodumene above 500 deg C i.e. traditional Roasting so no big deal other than a potentially lower price for the Petalite concentrate because of lower grade IMO.

The main game is 6% Spodumene, but if there's a credit in selling 4% Petalite then its unlikely you'll through it away. Bit like processing for gold and getting some silver credits as the ore type changes. Is it a major problem if its only a small and known portion of the ore body? Nothing a financial model won't address IMO.