cinereal

To make matters worse, there's an alternate form cinereal defined as 'cinereous.'

languagehat.com: ASHES TO ASHES. 2004

Burnett to restrain the roving eyes of the congregation and make gallants better attend to their devotions; all these, in addition to the memorial slabs and tablets, and weeping angels over cinereal urns, tend to give the church that air of ugliness and comfort which the modern churchman detests.

She and I, Volume 1

His cinereal ashes may lie beneath the cypresses, near the dust of the “Adonais” of his muse, under Roman sod, and where he said:

Percy Bysshe Shelley as a Philosopher and Reformer Sotheran, Charles, 1847-1902 1876

His cinereal ashes may lie beneath the cypresses, near the dust of the

Percy Bysshe Shelley as a Philosopher and Reformer Charles Sotheran 1874

"Why, the ashes of the dead were collected and preserved in these cinereal urns; and what are ashes but earthy salts?

Hollowdell Grange Holiday Hours in a Country Home George Manville Fenn 1870