The Siliqua denomination
The siliqua is the modern name given (without any ancient evidence) to small, thin, Roman silver coins produced in the 4th century A.D. and later.

When the coins were in circulation, the Latin word siliqua was a unit of weight defined as one twenty-fourth of the weight of a Roman solidus.
Siliqua
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An AR Siliqua struck AD 357-361 in Arelatum
Obverse: D N CONSTANTIVS P F AVG, pearl-diademed, draped and cuirassed bust right

Reverse: VOTIS XXX MVLTIS XXXX in four lines within wreath; SCON in exergue

Diameter: 17 mm
Die Orientation: 11 H
Weight: 1.82 g
No notes for this coin
RIC 261 and 291; RSC 342-3r; Sear 17951
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An AR Siliqua struck 351-355 AD in Thessalonica
Obverse: pearl-diademed head right; D N CONSTAN_TIVS P F AVG

Reverse: VOTIS / X X X / MVLTIS / XXXX within wreath; TES

Diameter: 21 mm
Die Orientation: -
Weight: 2.8 g
ex Aurea
RIC 163; C. 341
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An AR Siliqua struck 347-350 in Antioch
Obverse: DN CONSTANTIVS P F AVG, diademed head right

Reverse: VOTIS XXV VOTIS XXXX, four lines in wreath. Mintmark ANT

Diameter: 20 mm
Die Orientation: -
Weight: 2.4 g
No notes for this coin
RIC VIII Antioch 106; Sear 17931
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An AR Siliqua struck 367-375 in Treveri
Obverse: Draped Bust right "DN GRATIANVS P F AVG"

Reverse: Roma seated facing on throne, looking left, holding Victory on globe and spear, left leg bare "VIRTVS ROMANORVM"

Diameter: 16 mm
Die Orientation: 0 H
Weight: 1.5 g
No notes for this coin
RIC 58a
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An AR Siliqua struck 375-378 in Aquileia
Obverse: DN GRATIANVS PF AVG, pearl-diademed, draped and cuirassed bust right

Reverse: RBS ROMA, Roma seated left on cuirass, holding Victory on globe and reversed spear

Diameter: 13 mm
Die Orientation: -
Weight: 1 g
No notes for this coin
RIC 15b
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An AR Siliqua struck AD 378-383 in Treveri
Obverse: D N GRATIANVS P F AVG, pearl-diademed, draped and cuirassed bust right

Reverse: VRBS ROMA, Roma seated left on cuirass, holding Victory on globe and resting on reverse spear

Diameter: 18 mm
Die Orientation: 6 H
Weight: 1.93 g
Gratian was just seven years old when his father, Valentinian I, made him co-emperor of the western Roman empire. Following the sudden death of his father, Gratian, now sixteen, found himself solely in charge. He was an early supporter of Christianity and did his best to stamp out old Pagan traditions wherever possible. This beautiful siliqua was minted in Augusta Treverorum (modern day Trier in Germany), which was operational from around AD 291. On the reverse, under the figure of Roma, we can see the mintmark TR for Trier. This is followed by PS, for pusulatum, and indicates that the metal is refined silver. Over time the coin has toned and developed a stunning rainbow-like iridescence. Ex. Naville Numismatics, Auction 32; Lot 584
RIC 64a; C 87; Sear 19966
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An AR Siliqua struck 360-363 in Lugdunum
Obverse: FL CL IVLIA-NVS PF AVG, right-facing draped bust

Reverse: VOTIS V MVLTIS X within wreath, mintmark LVG

Diameter: 17 mm
Die Orientation: 0 H
Weight: 1.5 g
No notes for this coin
No references provided for this coin
(8) Valens
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An AR Siliqua struck 364-378 in Antioch
Obverse: Draped and cuirassed bust right " DN VALENS PF AVG"

Reverse: within wreath "VOT X MVL XX"

Diameter: 18 mm
Die Orientation: 0 H
Weight: 1.2 g
No notes for this coin
RIC 33b
(9) Valens
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An AR Siliqua struck 364-378 in Sirmium
Obverse: DN VALENS PF AVG, diademed, draped and cuirassed bust right

Reverse: VOT V MVLT X in wreath

Diameter: 18 mm
Die Orientation: -
Weight: 1.7 g
No notes for this coin
RIC 19b, Seaby 93a
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An AR Siliqua struck AD 366 in Lugdunum
Obverse: D N VALENTINIANVS P F AVG, diademed, draped and cuirassed bust right

Reverse: RESTITVTOR REI P, Valentinian, in military attire, standing facing, head right, holding labarum and Victory on globe; SLVG• in exergue

Diameter: 17 mm
Die Orientation: 6 H
Weight: 1.69 g
No notes for this coin
RIC 6c; Sear 19365