One who finds a treasure in a thing that belongs to him or to no one acquires ownership of the treasure. If the treasure is found in a thing belonging to another, half of the treasure belongs to the finder and half belongs to the owner of the thing in which it was found.
A treasure is a movable hidden in another thing, movable or immovable, for such a long time that its owner cannot be determined.
La. C.C. § 3420