I sent an email to MAC specifically asking about teal pigment being discontinued and this was part of the reply:

'Unfortunately, we are not able to supply you with Frost Pigment - Teal,
since production has stopped and all inventories have been completely depleted.'

I am absolutely gutted - I'm revising for exams and haven't really got the time to go out and buy it - that is if any are left in the stores. It was prob my fav pigment and the best green I've ever come across. Maybe its different in the US...