I think we have members here than can date your cob. What you have appears to be a "Pillars and Waves type" Spanish cob. One side has a pair of pillars with waves and two horizontal lines forming a tic-tac-toe design. The other side (2nd pic) displays a cross with lions and castles in the four quadrants.
The more I learn about Spanish colonial cobs the more I realize how little I know lol. That being said, my guess its struck at the Potosi or Lima mints in the time period of 1651 to 1773. These are typically degrading in quality throughout the time period which may help pin it down.
The date appears to end in a 6 but I could be wrong.