The Future, page-6

Correction as to current pollucite mines. The Bitka mine is in Zimbabwe and only seems to operate intermittently. The other is the Cabot mine in Canada which is the one under a lake. As far as I can find out it has not operated, under order of the authorities in Canada, since 2014 and possibly before. Cabot are operating on existing stocks and from previous announcements they will shortly run out. Of course they recycle the caesium formate and only have to replace losses, so can continue to operate on diminishing supplies for some time but the shortage will soon get pretty desperate. It would appear that the lack of supply is stopping the further development of uses in solar cells and shale drilling. It looks like a case of lack of supply discouraging development of exciting new uses.