Well, its not that dirty, but its got some stuff encrusted on it. I'm not that experienced in cleaning coins so the most I would do may be to soak it in distilled water. Let me know if I should attempt to clean the coin. Faustina I, Denarius 141 A.D. / AR17 , 3.4g O: DIVA FAVSTINA, draped bust right R: AVGVSTA Juno, veiled seated right, holding scepter RIC 363
Some of the encrustation should come off the obverse. I would tend to leave the reverse alone. You could use distilled water, or you could try the olive oil and lemon juice method. In a pan of simmering water, put a small container containing some olive oil and a few drops of lemon juice. Drop in the coin and let it simmer for about 10 minutes or so. Keep an eye on it. Take it out periodically, brush and put it back in. Repeat until you are satisfied.
I'd definitely try a distilled water soak. Perhaps @YOC and @Pishpash will weigh in. They have more experience with cleaning coins than do most of us. Edited: Pish replied while I was typing
Toothbrush is perfect. Just cut the bristles down by about half so that they are a little stiffer. I get mine from a local supermarket. 10 for 1GPB.
Congrats icerain => that's a sweet Faustina Senior!! I also happen to have one of that girl's coins ...