Knight’s Salvation Mountain is a monument of American folk art, hailed by congresswoman Barbara Boxer – who led the petition to have Salvation Mountain enshrined as such – as ’a unique and visionary sculpture encompassing five acres’, an ’iridescent fusion of doves, clouds, flags, flowers, hearts, streams and Biblical messages’.

iridescent (adj) : having colours like the rainbow; exhibiting a play of changeable colours; nacreous; prismatic; as, iridescent glass – source: Observer Magazine 23.3.2003, p. 26