1) When the broad markets drop hard, gold bullion rises due to the 'safe haven' factor. Mining stocks drop, pulled down by the market dump.
2) When the broad markets rebound and spring back hard, gold drops due to the reversal of its safe haven role. Mining stocks drop, pulled down by the gold dump.
UPDATE: Long-term reader and mailpal JH writes in:
Merci monsieur"(Y)ou forgot the third observation:When the price of gold rises so much that even dogs become profitable, Mining executives waste half the money and pocket the other half."