Andy,
There is no discount for private minerals! Exploration companies will pay up to an economic limit they set internally depending on there confidence in their project. it is up to you to get them there without listening to the lease brokers. Also read these pages and understand how a real exploration company will pay you for your lease.
If you want to make a fair deal after 12 years of waiting and worrying, Contact me by PM with some land particulars and I'll try to set you off in the right direction for you not the lease broker's sales pitch or a supposed exploration company's promises.
AndyB said:
Thank you Gary. Given properties that are close (within the same township or 8 or 9 sections away) should the discount on a private lease be 15/30/50% or more? Our particular rights have been leased by the same outfit for over 12 years, so they should be comfortable with the title issues.