I find it odd we have no one here to answer this question about the extra. It not really a conspirarcy. Gold production over the year uses a slime process to extract the gold. Once a year the  slime is collected and shipped and process.  I think it called

all slime cyanidation CIP process for gold mining / cyanide/ cyanidation 

 

Sound nasty, once a year the slime is process making gold.