The warehouse receipt demonstrates the value of the concentrates to be $3.7 million.
They're pretty clever - they worded it way on purpose. They did not state a grade of the concentrate, so no one can ever accuse them of lying about that. They also did not directly say what the concentrates are worth - they only say what is on a "warehouse receipt".
They also do not even say what exactly is in the concentrates. Gold? Silver? Platinum? Rhodium?