You probably heard what Milton Friedman had to say. That historically silver has been the coinage for everyday transactions while gold is for bankers making settlements with other bankers and for large commercial transactions. During a future SHTF and chaos using 90% silver and USG one ounce silver is better than using gold coins which will attract too much attention to you, your family and where you live. Using silver will also attract unwanted attention but not as much
Using 1964 dimes is probably safest.