Unusual piece of metal found

Does anyone know of a metal sold in the 1940’s or perhaps 1950’s as
"crinkle silver". I recieved a 4"x6" piece of the stuff from an
elderly woman who said it was given to members of a long defunct
jewelery making club in the Northeast US as a holiday gift in about
1950 something. It is unusually lightweight for silver,a very glossy
& brilliant silver colour, tests as .999 fine silver (using acid
testing), is extremely annealed and work hardens very slowly.The
piece is rolling mill smooth on one side and the reverse seems as
though flakes or crystals of [the material] have been compacted
together as a vacum machine would produce with an almost striated
look lengthwise on the sample.I tried to take a photograph to attach
but the reflection was too intense to warrant the repeated tries at
getting it visible enough to demonstrate…- in other words ; after
20 minutes i gave up the effort! So any ideas anyone???

R.E.Rourke

Aluminum alloy?

Ringman