The technique of beating gold into very thin sheets was depicted in
the 15th century BC in Egypt. Wall scenes from the tomb of Rekhmire,
showing different steps in ancient metalworking, include a stone
topped with layers of gold plates, goldbeater’s skins, and a stone
hammer. In ancient Mesopotamia, “Gold was beaten into very thin
sheets. from its earliest appearance there in the fourth millennium
BC…” (PRS Moorey, Ancient Mesopotamian Materials and
, p. 226). There is no definite evidence for Mesopotamian
use of the goldbeater’s skin, but Moorey cites one of the scholars
examining gold beads from the Royal Cemetery at Ur, “…‘beads of
bituminous shale, wood, etc., have been found covered with gold which
is so thin that when removed and held by one end it hangs down,
possessing insufficient rigidity to remain horizontal’.”

Judy Bjorkman (who envies Egyptologists for tomb paintings showing
metalworking; I’ve not found a single one for Mesopotamia, and I’ve
looked for over 40 years)