"Seriously how can this single page ann, that is very non...

"Seriously how can this single page ann, that is very non specific on details and not all DOOM - cause a 40% day fall?"

Because it is very non specific on details! They could have summed it up differently:

When we dug the stuff out of the ground for the stockpile, somehow we got the grade wrong, but we don't know how wrong, or if we do know, we're not telling you because the share price might REALLY collapse then. But then, shock-horror, we found that the grades from the pit, you know, that pit we dug the stockpile from, well, THOSE grades aren't right either! Now, who would have thought that? Two lots of ore from the same source, and both grades are "variable" (which is our cautious way of saying "lower than expected" - we said that too, mind you, but we think "variable" is a better term).

But, don't worry, the best way to sort out lower than expected grades is by redesigning the pit. That'll get the grades up! Fortunately we've got heaps of cash left over from that capital raising, so we've time to work out a better shape while still meeting our hedges and payroll, and we're still working to improve the extraction of whatever silver IS in the ore.