Comment 12 for bug 1448407

why do you call gvfs-mime there? it's to know what program is associated to open the file, nothing to do with the icon, that command works on mimetype, e.g "gvfs-mime --query application/vnd.oasis.opendocument.spreadsheet" should work

nautilus looks at the corresponding icon in the theme, e.g
$ find /usr/share/themes/<icon_theme_name> -name application-vnd.oasis.opendocument.*