The Market Capitalization of Silver is currently arround $1.376 T.
This value was obtained by multiplying the current silver price ($25.19 per once) with the amount of silver that is estimated to have been mined so far.
The amount of Silver that is estimated to have been mined is 1,700,000 metric tonnes. Note those values are approximations and that estimating the Market Cap of silver is more complicated than for Gold.
Note also that a large quantity of silver has been lost/destroyed due to industrial applications.
See also: The Market Capitalization of Gold