1877-Ca GR NGC AU Mexico 8 Reales Chihuahua Mint Scarce Silver Coin (24040203C). Almost Uncirculated Mexico 8 reales silver coin Struck at the Chihuahua Mint (Ca mint mark), assayer GR. During 1877 four assayer groups were used, GR is difficult to find! Certified by NGC to AU Details Cleaned (not distracting). Some luster, very nice in hand. Dunigan Ca54: "Scarce. This coin is the second most difficult of this year. The average condition for this coin is Very Fine. Part of this issue went to the Orient and were well used."