We don't have synonyms for marmoreally yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are marmoreal, arboreally and armorially.
"1949: If, as I said, his fingertips arrived at this, perhaps her flesh, marmoreal and lazy, was hardly aware that these were, in fact, fingertips, and not for example, nails or knuckles. - Italo Calvino, Difficult Loves"
"1949: If, as I said, his fingertips arrived at this, perhaps her flesh, marmoreal and lazy, was hardly aware that these were, in fact, fingertips, and not for example, nails or knuckles. - Italo Calvino, Difficult Loves"