So the coin is a Magnentius Large chi rho

with

on its left and

on its right, on the bottom is the Mintmark but I'm having trouble Identifying the specific one. (Coin is 28mm)
I've attached a few pictures of the coin, on the very left of the mintmark I've Identified a letter but completely clue less as to what it is, in the middle it could be an

or a

, on the right its an R or a

and on the far right I believe is a simple

(dot).
Any help is appreciated, thank you!