It is around 5mm and weighs less than 0.05g (my scale doe not have that resolution). It is a Ban Liang presumably from the early Han Dynasty. I have no idea how it would have been used. I assume a tiny cast.
Congrats, RAG ... nice lil' OP-sweetie Ummm, man I have so many wee ones ... => here are a couple of today's favourites Mysia, KyzikosAR Hemiobol Date: 600-480 BC Diameter: 6.51 mm Weight: 0.23 grams Obverse: Tunny fish right Reverse: Quadripartite incuse square References: Other: Some deposits ISLANDS off THRACE, Thasos AR Sixteenth Stater – Hemiobol Circa 500-480 BC Diameter: 8 mm Weight: 0.56 grams Obverse: Two dolphins swimming in opposite directions; pellets around Reverse: Quadripartite incuse square Reference: Le Rider, Thasiennes 9; HGC 6, 337 Other: VF, toned, light porosity. IONIA, Ephesos, AR Tetartemorion Circa 500-420 BC Diameter: 5 x 8 mm Weight: 0.17 grams Obverse: Bee Reverse: Head of eagle right within incuse square Reference: Karwiese Series IV; SNG Kayhan 126–34 Other: 12h … Good VF, toned, Exceptional for issue CARIA, Idyma. AR Hemiobol 5th century BC Diameter: 8 mm Weight: 0.44 grams Obverse: Land tortoise with segmented shell Reverse: Leaf, pellet Reference: SNG Ashmolean 228; SNG Kayhan 1627 = CNG 72, lot 803; Klein 522 Other: 11h … VF, toned, slightly granular, reverse off center. Very rare IONIA, Erythrai. AR Hemiobol Circa 480-450 BC Diameter: 6 mm Weight: 0.29 grams Obverse: Rosette Reverse: Simpler rosette within incuse square Reference: SNG Copenhagen –; Klein 387 Other: VF … slightly porous. Well centered MACEDON, Mende. AR Tritartemorion Circa 460-423 BC Diameter: 10 mm Weight: 0.62 grams Obverse: Ass standing right Reverse: Crow standing left within incuse square Reference: SNG ANS 358 (same obverse die) Other: 11h … VF, toned. Good metal MACEDON, Eion, AR Obol? (Tritartemorion?) Circa 460-400 BC Diameter: 10 mm Weight: 0.37 grams Obverse: Two geese standing right; ivy leaf and H to left Reverse: Quadripartite incuse square Reference: SNG ANS –; SNG Copenhagen 181 Other: VF, toned, typical porosity PHOENICIA, Tyre. Uncertain king. AR Twenty-fourth Shekel Circa 393-311/0 BC Diameter: 7.2 mm Weight: 0.46 grams Obverse: Dolphin leaping right Reverse: Owl standing right, head facing; crook and flail in background Reference: E&E-T Group III.1.2.d, 1655-1710; HGC 10, 329 corr. (denomination) Other: 6h … VF, toned, minor porosity. Choice for issue Phoenicia, Sidon, 1/16 AR Shekel 401-366 BC Diameter: 8.35 mm Weight: 0.72 grams Obverse: Galley left Reverse: King slaying erect lion References: Other: Cool reverse Hey, I am a huge fan of the wee ones ... => congrats again RAGNAR ... cha-ching