|Christie's says the mask dates to a time when complex societies were first evolving [Credit: Reuters/Christies]|
The mask is the oldest art object ever offered at Christie's auction house in New York.
Christie's antiquities department head Molly Morse Limmer says it is one of the earliest sculptural types to survive from antiquity.
"Only very few of these masks are known," she said.
"All were found in the Judean desert, all were carved of limestone, and all represent the human skull."
The Judean desert's extreme dry conditions helped preserve the mask.
Its function is a mystery, but Ms Limmer says its origins date to a time when complex societies were first evolving.
"No doubt they represent one of the earliest human attempts to connect with the spiritual world," she said.
"Given the skeletal representation, it would be logical that they relate to death rituals or ancestor worship."
The auction house says small holes drilled along the perimeter suggest that hair might have been added, or they might have been used to secure the mask on the face of a dead person, or to a wall, pillar or statue.
The 22.8-centimetre mask, which is being sold by a New York collector, is expected to fetch up to $US600,000 at auction in June.
Reuters The Archaeology News Network