If you’re thinking about donating land as a conservation easement but don’t own the subsurface (known as “severed mineral rights”), then you’ll need an assessment of the land’s mineral potential to determine whether the easement will qualify as a charitable tax deduction. Geologists at the Wisconsin Geological and Natural History Survey perform this service. Learn how we prepare mineral assessments and their limitations as well as the basics about severed mineral rights, mineral deposits, and conservation easements.