@chronos, with this high level of wear, it is impossible to know what has added that "extra" metal. It might be brazing from a mount as this piece could have been made into jewelry at one time. Those parallel lines at nine o'clock on the obverse are interesting to look at but are also just damage.
"If you climb a good tree, you get a push." -----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed." -----King Adz