Primary silver futures contracts are March, May, July, September, and December. Other months also trade, but with lesser volume and open interest.
https://www.cmegroup.com/markets/metals/precious/silver.quotes.html
https://www.investopedia.com/articles/optioninvestor/06/goldsilverfutures.asp
The most active months for delivery (according to volume and open interests) are March, May, July, September, and December
SI contract, ticksize 0.005, pointvalue 5000
SIL contract, ticksize 0.005, pointvalue 1000
Futures Close-Out Policy (IB) type in symbol in search bar SI or SIL
SI and SIL TERMINATION OF TRADING: Trading terminates at 12:25 p.m. CT on the third last business day of the contract month.
"Most studies agree gold is overall the more rare of the two metals; however, above ground silver is actually more rare than gold. Estimates report gold is 5-7x more abundant above ground than silver. Beneath the surface, silver is approximately 19x more abundant than gold." (Google it for the source)
"Silver is 17.5 times more abundant in the Earth's crust than gold. But the amount of above-ground gold available far exceeds that of silver. " (Google it for the source)