Qenya
tinko
noun. metal
tinkotéma
noun. t-series
rauta
noun. metal
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A noun for “metal” in The Etymologies of the 1930s derived from the root ᴹ√RAUTĀ of the same meaning (Ety/RAUTĀ). In that document, its Noldorin cognate was the basis for the second element of the names Finrod, Angrod and Damrod. In Tolkien’s later writings the second element of these names were based on S. raud “noble”. For purposes of Neo-Quenya I think it’s better to stick to Q. tinco “metal” from Appendix F of The Lord of the Rings.