If I search google for this string, your post is the only one that comes up. How did you arrive at this figure?
In the history of industry, when has it ever been a positive indication that only two players control the majority of the supply?
Do these companies directly own the mines or are there partnerships and subsidiaries involved? What countries are they operating in? How long is the supply chain from the mine to the product?
How are water rights being managed? Is there correct oversight? Are any governments trading long term environmental damage for short term profits? What happens when the mines are depleted?