Descrizione sommaria:
D. SABINIA TRANQUILLINA AVG². Tranquillina, busto diademato e drappeggiato a destra sopra falce lunare.
R. CONCORDIA AVGG³. La Concordia degli Augusti, assisa a sinistra con patera nella mano destra e doppia cornucopia nella sinistra.

La ricerca nel web di monete di tipologia simile a quella di figura ha dato luogo ai seguenti risultati:

1. ancient-roman-coin.com Silver Antoninianus [denario, a mio avviso]. - Tranquillina (242 to 244) - Antioch RIC IVc 249 [Gordian III], Cohen 1 - 3,6g - 22mm - R4. tranquillina roman coin antoninianus. Obverse: SABINIA TRANQVILLINA AVG, Draped bust right, wearing stephane, set on crescent. Reverse: CONCORDIA AVGG, Concordia seated left, holding patera and double cornucopiae. Coin value: 17 262 USD (2010).
   
2. https://www.cngcoins.com/Coin.aspx?CoinID=127687 Extremely Rare Tranquillina Antoninianus. Sale: CNG 79, Lot: 1176. Estimate $7500. Closing Date: Wednesday, 17 September 2008. Sold For $8600. Tranquillina. Augusta, AD 241-244. AR Antoninianus (2.16 g, 7h). Rome mint. Special emission, AD 243. Draped bust right, wearing stephane, set on crescent / Concordia seated left, holding patera and double cornucopia. RIC IV 249; RSC 1. Good VF, toned, minor porosity. Extremely rare. From the Gordon S. Parry Collection. Ex Jacquier FPL 15 (Summer 1993), no. 384.
3. https://www.britishmuseum.org/collection/object/C_R-496 Museum number R.496. Denomination radiate. Description: Silver coin. (whole). Concordia seated left, holding patera in extended right hand and double cornucopia in left hand. (reverse). Bust of Tranquillina, draped and diademed, right; crescent behind bust. (obverse). State Associated with: Roman Empire. Authority Ruler: Gordian III. Cultures/periods Roman Imperial. Production date 241-244. Production place Minted in: Rome (city) Europe: Italy: Lazio: Rome (province): Rome (city) Materials silver. Dimensions Die-axis: 12 o'clock. Weight: 4.40g. Obverse Inscriptions: SABINIA TRANQVILLINA AVG. Reverse Inscription: CONCORDIA AVGG. Bibliographic references: RIC4 / The Roman imperial coinage, vol. 4: Pertinax - Uranius Antonius (249, p.41). Registration number R.496.
4. https://gemini.bidinside.com/en/lot/399/rare-and-mint-state-tranquillina-denarius-/ LOT 401 - AUCTION GEMINI XII. Estimate: 12.000,00 USD. Starting price: 9.600,00 USD. RARE AND MINT STATE TRANQUILLINA DENARIUS. Tranquillina, Wife of Gordian III. - Denarius, 3.30g (8h). Rome, after 241 AD. Obv: SABINA TRANQVILLINA AVG Draped bust right wearing stephane. Rx: CONCORDIA AVGG Concordia seated left holding patera and double cornucopia. RIC 252 (R4). Mint State. Notes: Very rare, both as a Rome-mint coin of Tranquillina and for its denomination. Cohen 1 values the corresponding antoninianus of Tranquillina at 800 francs, ten times his base price for an aureus of Gordian III, but the denarius of this empress was unknown to him. Gordian III had struck denarii as his regular silver denomination for a few months in 240, but by 241 when he married Tranquillina he had reverted to the antoninianus as standard silver coin, and the denarius had become a rare special denomination probably struck for distribution on special occasions, like the silver quinarius. The surviving Rome-mint coins of Tranquillina can be interpreted as a special issue for her marriage to Gordian in 241, after which her father, Gordian's praetorian prefect Timisitheus, apparently turned down the honor of coinage at Rome for his daughter, though provincial mints struck for her in considerable volume.
5. https://www.numisbids.com/n.php?p=lot&sid=1980&lot=571 Lot 571 Estimate: 6000 CHF. Price realized: 5500 CHF. Tranquillina, third wife of Gordian III. Antoninianus or double-denarius 241, AR 3.79g. SABINA TRANQVILLINA AVG Diademed and draped bust r., on crescent. Rev. CONCORDIA AVGG Concordia seated l., holding patera and double cornucopiae. C 1. RIC Gordian 249. Very rare. An appealing portrait and a lovely light iridescent tone, extremely fine. Ex Gorny & Mosch 114, 2002, 385 and NAC 87, 2015, 321 sales. The coins of Tranquillina are inexplicably rare. They include the full range of denominations then being struck for her husband in silver and bronze, lacking only gold coins or medallions. Though Tranquillinas series shows every sign of being the first output of a substantial coinage, it must have ceased after the initial issue.Tranquillina was the daughter of Timesitheus, whom Gordian III made commander of his praetorian guards in 241; his appointment must have occurred contemporarily, or just prior, to the royal wedding in May 241. Celebrations were probably brief as Gordian, Timesitheus and Tranquillina soon marched east at the head of an army to answer the invasion of Roman Syria by the Persian king Shapur. To have arranged his own high appointment and the marriage of his daughter to the emperor, we may be sure Timesitheus held sway over the timid boy-emperor. It remains a mystery why Tranquillinas coinage ended as soon as it began, for Timesitheus remained praetorian prefect until his death two years later, and Gordian remained married to Tranquillina for the remaining three years of his own life.
6. https://leunumismatik.com/de/lot/11/705 Los 705 Tranquillina, Augusta, 241-244. Denarius (Silver, 20mm, 3.00g, 2h), Rome, mid 243. SABINA TRANQVILLINA AVG Draped bust of Tranquillina to right, wearing stephane. Rev. CONCORDIA AVGG Concordia seated left, holding patera in her right hand and double cornucopiae in her left. Cohen -. RIC 252. Extremely rare and in exceptional condition for the issue. A wonderful, lightly toned and lustrous coin with a charming portrait of great beauty and undoubtedly among the finest known. Very minor flan flaw on the edge, otherwise, good extremely fine. Ex The New York Sale XXXIV, 6 January 2015, 649, from the Barry Feinstein Collection, Numismatica Ars Classica 39, 16 May 2007, 153 and previously acquired from Harlan J. Berk. Tranquillina was the daughter of Gaius Julius Timesitheus, an eques who had a sucessful career under the Severans and Maximinus before he finally became the Praetorian Prefect of the juvenile Gordian III in 241. As the de facto-ruler of the empire, he had his daughter married to the emperor and acted as the protector of the imperial couple. Timesitheus appears to have been an effective administrator and general, but he eventually died under suspicious circumstances after defeating a Sasanian army in 243. His successor was Marcus Julius Philippus, who assumed the throne few months later after Gordian III had also conveniently died afield. Whatever the role of Philip in these suspicious events, Tranquillina herself consequently disappeared from all sources without a trace. Schätzpreis (prezzo stimato): 15000 CHF. Startpreis: 12000 CHF. Zuschlag (aggiudicato): 17000 CHF.
7. https://www.gazette-drouot.com/en/lots/9324835 Lot n° 125 EMPIRE ROMAIN Bidding closed. Result: Not available. Tranquillina (241-244) Femme de Gordien III. Denier, Rome. Av. SABINIA TRANQ-VILLINA AVG Buste diadémé et drapé de Tranquilina à droite. Rv. CONCORDIA AVGG La Concorde sur un trône, tenant une patère et une double corne d’abondance. RIC. 252. 20mm. 2,56g. Infime éclat de frappe, TTB à Superbe.
8. http://numismatics.org/collection/1944.100.19967 Avers/Droit: SABINIA TRANQVILLINA AVG - Bust, diademed, draped right, on crescent. Revers: CONCORDIA AVGG - Concordia, seated left, holding patera in right and double cornucopiae in left. Description physique: Axe: 2 Etat de conservation: Usure: cleaned with duraglit wadding silver polish and e-zest jeweluster for coins; washed by soaking in hot and cold baths of distilled water and ethyl alcohol. Dimensions Poids: 4.19. Diamètre: 21.5. Description typologique Intervalle chronologique: AD 238 - AD 244. Type d'objet: Monnaie. Technique d'émission: Frappé. Dénomination: Antoninien. Matériau: Argent. Autorità emettitrice: Gordien III. Géographique Atelier: Antioche. Région: Syrie. Avers/Droit. Symbole: 9334. Portrait: Tranquilline. Revers Divinité: Concordia.
9. https://www.ikmk.at/object?lang=en&id=ID123066 Tranquillina 241–244 n. Chr. Münzkabinett, KHM. Inventory no RÖ 36981. Obverse SABINA TRANQVILLINA AVG. Büste der Sabinia Tranquillina nach rechts mit Drapierung. Reverse CONCORDIA AVGG. Concordia nach rechts auf Thron sitzend, hält Patera und cornucopia (Füllhorn). Sitter/s. Sabinia Tranquillina. Authority Gordianus III. 241–244 n. Chr. Denomination Doppeldenar. Material Silver Production struck. Weight 3,16g Diameter 20,6mm. Die-axis 7h. Mint Rom Publications: RIC IV, III, 249; C, 1.
   

Un saluto cordiale.
Giulio De Florio

---------------------------------------------------
Note:
(1) Antoniniano. L'antoniniano si distingue dal denario per la presenza di una corona radiata sulla testa del sovrano; però, quando nel dritto è raffigurata l'imperatrice, non essendo accettabile nell'ottica romana che una corona possa cingerle la testa, l'elemento di distinzione tra i nominali è assicurato dalla falce di luna collocata negli antoniniani sotto la testa dell'imperatrice. Nella tabella sottostante ho riportato le caratteristiche fisiche delle monete di cui ai link sopra menzionati