Re: USAGE: YAEUT: "Molten" vs. "Melted"

H. W. Fowler. A Dictionary of Modern English Usage:

"Molten, apart from its use as a poetic variant of melted, is now
confined to what needs great heat to melt it. Molten iron, melted
butter."

Shorter Oxford English Dictionary:

"molten. adjective
Liquefied by heat; in a state of fusion. Chiefly (connoting a higher
temperature than melted) of metal, rock, etc."

These definitions work for me.