I have developed a new sub-collection (as if I needed another one!), which is the eastern denarii of the emperor Hadrian.
The following three paragraphs paraphrase the description of these eastern coins by the numismatist Curtis Clay.
Hadrian's main issue of Eastern denarii seems to have been produced circa A.D. 129-131 in connection with his second great provincial tour.
The types on both sides of the coins generally copy those of Rome.
The usual obverse legend is HADRIANVS AVGVSTVS P P, which was used at Rome in A.D. 128-9. Considerably rarer are Eastern denarii with the obverse legend HADRIANVS AVGVSTVS or HADRIANVS AVG COS III P P, the first of which was used at Rome circa A.D. 125-8 and then again circa 129-131, and the second of which was Hadrian's latest obverse legend at Rome, used from circa 131 on.
I have obtained a few examples but wanted to share my most recent addition to this section of my collection.
Hadrian Denarius
Obv:- HADRIANVS AVGVSTVS, Bare headed, draped and cuirassed bust right, seen from the rear
Rev:- COS III, Mars walking right holding spear and trophy
Minted in an Unknown Eastern mint.

Strack made a study of the known examples. The following information was provided by Curtis Clay in a discussion about this coin:-
"Strack *13, pl. XX, has this rev. type in the rare HADRIANVS AVGVSTVS issue, citing a denarius in Paris with bare-headed, draped bust r., not draped and cuirassed like yours. The same rev. type also occurs on Eastern denarii with the normal obv. legend H A P P.
Strack doesn't record your exact obverse with any other rev. type in this H A issue either. However, I have two Eastern denarii with the same obv. type, but from a different obv. die, coupled with two other COS III rev. types."
I think it is a beautiful and interesting coin. The fact that it is completely unlisted and rare is just an added bonus.
Regards,
Martin