The answer above relates only to a sale of the position. If sold the gains would be taxed at the personal tax rate as the investor is presumed to actually holding silver bullion. I actually found a relevant answer to my question as to how to treat gains while holding the position in an old TT post (located by a Google search). There is a rather tedious means (using a Cost Basis calculate) to determine each of the cost bases. In my case, the gains are so negligible and any loss not to be taken that it is best to simply consider the cost basis as 0. This is probably the case of most filers in this situation.
