Silver.
This was a source of wealth from early days. Abraham was rich in silver, Genesis 13:2; but with Solomon gold was so plentiful that silver was 'nothing accounted of.' 1 Kings 10:21. The silver and gold which he had amassed were, alas, afterwards carried away to enrich their enemies because of the sins of Israel. 2 Chronicles 12:9. Silver was also the common specie of commerce, 'pieces of silver' being weighed long before money was coined. Genesis 23:16. Silver was used for the sockets, hooks, etc., in the tabernacle, the money paid for the redemption of the Israelites being applied to this purpose. Exodus 30:11-16; Exodus 38:25-28. The house of God is founded on redemption. Exodus 36:24-36; Exodus 38:10-17.
Silver is found in the earth (Job 28:1), and before it can be compared to 'the words of the Lord' it must be purified seven times. Psalms 12:6; Proverbs 25:4.
THE SILVER CORD in Ecclesiastes 12:6 seems to refer to 'the thread of life,' which is loosed, or removed, when death ensues.