MadameCurie actually, you are thinking of Egypt's Chambers of Fortune, aren't you? While I have done that one sometimes, for tin, iron ore and coal, there are 3 more in my Materials Mines, each of which uses 17 green rings
- the Palace of Fortune that comes with China
- the Reef of Fortune that comes with Atlantis
- the Temple of Fortune that comes with Greece
They all give 3 chests of coin., plus
China: Dragon ingots, ancient scrap metal, bamboo, rice, shiitake, eels, shale, coal.
Atlantis: black Pearl, orichalcum, volcanic ore, marble, lobster, seaweed
Greece: adamantine steel and ore, orichalcum, marble, octopus, lemon, olives, eels & lobster, volcanic ore, cedar wood
Green rings are worth a lot, especially double materials weeks.
When I have surplus lemon and olives, I buy pillars with them.
My usual pillar items are:
Adamantine steel: 1000 yield 55 million energy
Dragon ingots: 1000 yield 16 million energy
Shale: 4000 yield 2,840,000
Bamboo: 4000 yield 2,720,000
Marble: 4000 yield 7,200,000 1p
Cedar wood: 4000 yield 11,400,000
Iron bars: 1000 yield 1,450,000 energy
Bronze bars: 1000 yield 1,000,000 energy
Coin: 1 million buy 1,000,000; 10,000,000 buy 10,000,000
Stone: 40,000 buy 2,000,000
Ruby, if I can save 350, gets 35,000,000