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.
glast
noun. marble
glastrin
adjective. marble
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 appearing as G. glast “marble” in the Gnomish Lexicon of the 1910s (GL/39), probably derived from ᴱ✶ʒalast- like its cognate ᴱQ. alas (alast-) “marble” in the contemporaneous Qenya Lexicon (QL/30).
Neo-Sindarin: I think this word may be salvageable in Neo-Sindarin as ᴺS. glast, reconceived as a derivative of ᴹ√GALAS “joy, be glad”, perhaps from ᴺ✶galast- originally with the sense “thing pleasant to touch”.