佛頂尊勝陀羅尼經教跡義記 2.167

2.167

述曰：第十、淨金為諭。言閻浮檀金者，《大智度論》云：「金有多種，一切現在金，不如佛在世金，一切佛在世金，不如閻浮檀金。」故以此金讚其德也。又說：「其金在於水底，光徹於外，輪王出世，此金方現。」

The commentary says: Tenth, using pure gold as an analogy. Regarding 'Jāmbūnada gold', the Dàzhìdù lùn says: 'There are many kinds of gold; all present-day gold is inferior to the gold when the Buddha was in the world; all the gold when the Buddha was in the world is inferior to Jāmbūnada gold.' Therefore, this gold is used to praise its virtues. It is also said: 'This gold lies at the bottom of the water, its light shining through to the outside; only when a wheel-turning king appears in the world does this gold manifest.'