Prt-634.
Photo from Album (2012), sale 12, lot 1289. tin 15 reis (10.82g), 1760, KM-138.1, date 1760 is possibly an error for 1769,

Wt = 13.61g. Diam = ~mm. D. José I 1769 15 Bazarucos (zinc)
Photo from Zeno posted by Quant Geek