I'm confused by the wording here. This is how I read the above sentence:The material seemed to be predominantly gold, though a weird lighter lustrousness hinted at some strange alloy with an equally beautiful and scarcely identifiable metal.
The material seemed to be predominantly gold. But it has a weird lustrousness. This means it also contain some strain alloy. This strange alloy is as beautiful and hard to identify as some other unknown metal.
There's no coherence in this. Why did a 3rd metal randomly popped up without being named? How is the comparison supposed to work if the equivalence is kept hidden?
Source: "The Shadow over Innsmouth" by H. P. Lovecraft