The hemiassarion was a bronze denomination worth ½ as - assarion in Greek.
It was commonly struck by Roman Provincial mints, and was not struck to a standard weight but rather to some local standard. It was simply a coin worth ½ of the local basic coin denomination.
It was commonly struck by Roman Provincial mints, and was not struck to a standard weight but rather to some local standard. It was simply a coin worth ½ of the local basic coin denomination.

(1)
Antoninus Pius

An
AE
Hemiassarion
struck 138-161 AD
in
Antiochia ad Maeandrum
Obverse: ΑV ΚΑΙ ΤΙ ΑΙΛ ΑΔ ΑΝΤΩΝƐΙΝOC, laureate head of Antoninus Pius, r.
Reverse: ΑΝΤΙΟΧƐΩΝ, Nike advancing, r., holding wreath and palm-branch
Diameter:
17 mm
Die Orientation: 12 H
Weight: 3.3 g
Die Orientation: 12 H
Weight: 3.3 g
Leu Numismatik is calling the metal bronze and the denomination Hemiassarion: https://www.acsearch.info/search.html?id=4765952
RPC Online IV.2, 816 (temp); BMC 34–5; Cop 51
(2)
Antoninus Pius

An
AE
Hemiassarion
struck 138-161 AD
in
Philippopolis
Obverse: ΑΥ Τ ΑΙ ΑΔΡΙΑ ΑΝΤΩΝΕΙΝΟϹ, Head of Antoninus Pius facing right, wearing laurel wreath
Reverse: ΦΙΛΙΠΠΟΠΟΛΕΙΤΩΝ, Ares (or Protesilaos) advancing left, holding shield
Diameter:
-
Die Orientation: -
Weight: -
Die Orientation: -
Weight: -
CC Vermeule suggests the figure is Protesilaos instead of Ares because:
"The hero Protesilaos was particularly venerated in Thrace and Thessaly. He was the first Greek to fall at Troy. Vermeule associates such figurative depictions on coins like this one with the Riace bronzes and justifies his identification of the figure with Protesilaos with the fact that Protesilaos, as the founder of the city, points to the ground, while Ares would adopt a fighting stance ("The God of war on the Borghese statue ... does not point downwards""
Varbanov 747; RPC Online IV.1, 7445 temp.
(3)
Commodus

An
AE
Hemiassarion
struck 177-192 AD
in
Petra
Obverse: ΑΥΤ ΚΟΜΜΟΔ ΑΝΤⲰΝΙΝΟϹ: laureate head of Commodus, r.
Reverse: ΠƐΤΡΑ ΜΗΤΡΟΠΟΛΙϹ: in laurel wreath
Diameter:
0 mm
Die Orientation: 6 H
Weight: 2.1 g
Die Orientation: 6 H
Weight: 2.1 g
No notes for this coin
RPC IV online 6633
(4)
Geta

An
AE
Hemiassarion
struck 198-209 AD
in
Marcianopolis
Obverse: draped bust right from behind; Π CEΠTI_ΓETAC K
Reverse: tripod, snake entwined around leg; MAPKIANO_ΠOΛITΩN
Diameter:
17 mm
Die Orientation: -
Weight: 1.74 g
Die Orientation: -
Weight: 1.74 g
No notes for this coin
Varbanov I 1117; AMNG I/I 703