Possible Clues:

• Source of riches
• An X might indicate one
• Box for valued items
• Pirate cargo certain to be packed in the crates at sea
• Astute research mistaken in dismissing a source of wealth
• This is valuable, the rest a curse, alas
• Box of wealth
• Precious box certain to be found in stretches of water, dry on the outside
• Source of wealth certainly within reach in cricket match
• That'll do for a hoarding