'Ashes' in the Bible

Daughter of my people, gird thee with sackcloth, and roll thyself in ashes: make mourning, as for an only son bitter lamentation; for the spoiler cometh suddenly upon us.

And the whole valley of the dead bodies, and of the ashes, and all the fields unto the torrent Kidron, unto the corner of the horse-gate toward the east, shall be holy unto Jehovah: it shall not be plucked up, nor overthrown any more for ever.