What might be the value of a small share of mineral rights in Harding County, South Dakota?
Explanation:
Through inheritance, I have possiblity of having ownship rights to minerals under 160 acres in Harding County. These right have already been divided 9 times, so my portion would be based on 1/9 of 160 acres.
The monthly dividend is about $30 after taxes.
I cannot find any record of any sales of mineral rights in Harding County.
The story:
I pursue this only because my parents, who left this to me in a will, knew of my interest in family history. The story goes that my great uncle won the land in a card game! 
The surface land was sold to a local rancher in 1987. I have visited Harding County offices and have copies of all documentation related to this land.
*My father had no other land or assests in South Dakota. All assests in his home state had been sold or transfered. Therefore there was no need to do a probate, which make this last bit of detail from his will quite complicated.