This is a lovely anthropomorphic clasp from the Early La Tène with the suggested date of 5th century BCE.
It is listed as a “garb cloak” and “celtic clasp with a human head (mask fibula) from a grave in Holderstüdeli.” The site it was found is in Switzerland.
Size is listed as 4.2 cm.
Credit for the item goes to the Archiv Archäologie BL.
Source for the item was found here.