I'm reading a book on chemistry at the moment. It has led my thoughts to alloys
1. Brass (copper + zinc)
2. Bronze (copper + tin)
3. Gunmetal (copper + tin + zinc)
4. Electrum (gold + silver + copper)
5. White gold (gold + nickel + palladium)
6. Steel (iron + carbon)
7. Stainless steel (iron + chromium + nickel)
8. Cupronickel (nickel + bronze + copper)
9. Sterling silver (silver + copper)
10. Pewter (tin + antimony + copper)
See this Wikipedia page here.
Bonhoeffer uses a similar phrase 'worldly Christianity'. It's J Gresham Machen that I want to line up most closely with. See his Christianity and culture here. Having done commentaries on Proverbs (Heavenly Wisdom) and Song of Songs (Heavenly Love), a matching title for Ecclesiastes would be Heavenly Worldliness. For my stance on worldliness, see 3 posts here.