Carausius, AR Denarius, 18mm, 3.70 g, 

IMP CARAVSIVS P F AVG, laureate, draped, cuirassed bust right.
CONCORDIA MILITVM, clasped hands.

Mintmark above: RSR (when the hands are correctly
positioned). 
RIC 548; RSC 24; Shiel 16-19.

Estimate £ 600-700 

Used with permission of CNG coins, www.cngcoins.com, Feb 2009
Sold for $570