Numbers 31:22
20 You must purify each garment and everything that is made of skin, everything made of goats’ hair, and everything made of wood.” 21 Then Eleazar the priest said to the men of war who had gone into the battle, “This is the ordinance of the law that the Lord commanded Moses: 22 ‘Only the gold, the silver, the bronze, the iron, the tin, and the lead, 23 everything that may stand the fire, you are to pass through the fire, and it will be ceremonially clean, but it must still be purified with the water of purification. Anything that cannot withstand the fire you must pass through the water.
1 Enoch 52:2
1 And after those days in that place where I had seen all the visions of that which is hidden--for I had been carried off in a whirlwind and they had borne me towards the west-- 2 There mine eyes saw all the secret things of heaven that shall be, a mountain of iron, and a mountain of copper, and a mountain of silver, and a mountain of gold, and a mountain of soft metal, and a mountain of lead. 3 And I asked the angel who went with me, saying, 'What things are these which I have seen in secret?' 4 And he said unto me: 'All these things which thou hast seen shall serve the dominion of His Anointed that he may be potent and mighty on the earth.'
Notes and References
"... the metals in question were essential to the wealthy, glorious, and powerful lifestyle and activity of the kings and the mighty. Second, gold, silver, iron, and bronze were among the materials from which idols were fabricated (Daniel 5:4, 23; 4Q242 frgs. 1-3, 7-8 with bronze and iron reconstructed from Daniel 5) ... This list of metals in verses 2, 6 is here altered, so that they appear in order of their 'value' (see also the order in Numbers 31:22). This has the effect of prioritizing gold and silver and the fearful plight of those who are associated with it and depend on it ..."
Nickelsburg, George W. E. A Commentary on the Book of 1 Enoch Chapters 37-82 (p. 191) Fortress Press, 2012