The gestation period for an elephant is 640 to 660 days. This is equivalent to about 95 weeks, or 22 months, and is the longest gestation period of any mammal.
Dimes dated after 1964 are copper-nickel clad and contain no silver. Quarters are also clad, except for the bicentennial commemorative coins with an S mint mark that were produced for mint and proof sets. Kennedy half dollars from 1965 to 1970 were 40 percent silver composition. After 1970, all Kennedy halves were clad, except the same S bicentennial issue.
90% silver quarters, half dollars and dimes were produced until 1964. From 1965-1970 half dollars have been 40% silver while dimes/quarters contained no silver. From 1971-pres â¦ ent no silver coins have been minted for circulation. Today the US mints various collector coins in silver, but none for general circulation.