Vintage 1940's Mexican Alpaca Silver Green Tribal Mask Earrings Screw Back Aztec

Vintage 1940's Mexican Alpaca Silver Green Tribal Mask Screw Back Earrings They are marked "Alpaca" on the backs which is not sterling I don't know what the stone is either glass, onyx or obsidian - unsure Could use a cleaning they are vintage They measure roughly an inch both ways