The stockpile amounts dropping was semi-expected due to the strip ratio increasing to over 5 for this month, however you're correct, they were a bit optimistic in their previous monthly announcement.
Here is the 'to date' strip ratio and AISC for BLK on a graph, with data reconciled below. I've also put the June quarter 'expected' in and it seems to line up with historical for this company. The variance from the line is likely caused by recovery which was the major disappointment for me in march but didnt expect the market to react like that.
Column 1
Column 2
Column 3
Column 4
Column 5
Column 6
Column 7
Column 8
Column 9
0
Jun-17
Sep-17
Dec-17
Jan
Feb
March
Total Mar 18
Jun-18
1
oz
15720
15619
14922
6498.2
6713.3
7419.2
20631
21000
2
Grade
1.281
1.4
1.135
1.36
1.542
1.597
1.504
1.6
3
AISC
1758
2236
1882
1158
912
1197
1092
1150
4
Milled
416.1
379.4
443
163
150
165
477
450
5
Rec
91.7%
91.5%
92.3%
91.2%
90.6%
87.8%
89.4%
92
6
SR
11.7
26.8
10.2
3.6
1.5
5.2
2.5
4.5
BLK Price at posting:
8.2¢ Sentiment: Buy Disclosure: Held