Vintage Mexican Silver Zippo Mayan Aztec Calendar

Up for auction is a vintage Zippo lighter. The insert says For best results use ZIPPO flints and fluid Zippo Mfg Co Bradford, PA Made In Zippo USA Pat 3517191 R. The case is nicely worked Mexican silver applied over the original case, so can't see the bottom markings to get exact date. The case has the Aztec/Mayan calendar and leaves on one side and monograms and leaves on the other. Bottom is marked Mexico, no Sterling, 925, 800 or any other mark, so unsure if Nickel Silver or Sterling, but very heavy with nice workmanship and detail. Has 5 barrel hinge, inside of case looks to be brass. Would guess the age to be from the late 1950's through the 1960's from the patent #. Insert is good, solid click, lid a little loose. Case has some wear and minor dings, but nice. Shipping is $4.60, well packed, priority mail, insurance extra. Email with any questions.