Mineral rights value

Hello, I’m new here and have a question. An offer has been given to me for my mineral rights in Angelina county. Wondering what royalties are normal over one year of a producing well. Also what is a fair amount per acre if I sell? Texas. Thank you.

British Petroleum, via Landman from NAC, offered $350/acre and 1/5 royalty and five years in Stanley Survey Southeast of Huntington. After I let him know it wasn’t my first rodeo, he increased offer to $500/acre. I know there is oil and lignite coal in this area and am not inclined to lease at that rate. I’ve got oil leases in other counties for that much per acre. 5 years is too long for a lease. They need to get in & drill or forget about it. 3 years should be lease term. Landman trying to rush the lease, says BP is only game in town and if I don’t go with them, then I’ll never see my property leased. Any comments??