Messenger of Allah ﷺ said, "No bloodmoney will be charged if somebody dies in a mine or in a well or is killed by an animal; and if somebody finds a treasure in his land he has to give one-fifth of it to the Government."  

قَالَ رَسُولُ اللَّهِ ﷺ الْمَعْدِنُ جُبَارٌ وَالْبِئْرُ جُبَارٌ وَالْعَجْمَاءُ جُبَارٌ وَفِي الرِّكَازِ الْخُمُسُ