Or possibly also in coldness, and if you extend the resemblance to a marble statue, aloofness. This has a lot of metaphoric possibilities, the more you think about it. How about in endurance? -- marble monuments, and all that (not that those would outlive Shakespeare's sonnet 55). From Latin marmoreus, from marmor, marble, first used in 1798.
Updike described her writing as marmoreal and elegant.