Answer:
The wife would have the right to grant mineral lease, receive bonus/rental money & potential royalties on her undivided 50% interest and the husband could do same with his 50% interest. The rights are owned separately and each party can do as they wish.
If the usufruct is over the mineral rights and not only the surface, the situation would be different. If need more information, visit me at louisianaenergy.ning.com