Looking at the hair, I thought it was Faustina I also. The reverse appears to be Juno but there is no legend. The closest I have found on Wildwinds is:
DIVA FAUSTINA SR., wife of Antoninus Pius. Died
141 AD. Æ Sestertius (31mm, 25.57 gm). Diademed
and draped bust right / Juno standing left,
holding patera and long sceptre. RIC III 1143
(Antoninus Pius); Cohen 210.
Sear Roman Coins and their Values (RCV 2000 Edition) Number 4629
But mine is bigger and heavier. Found similar coins on Tantalus, but the reverse was listed as Juno, Ceres, Letitia among others, and few bothered to put weight or measurement in.
Just measured the edge and at the thickest part it is 4 or 5mm.