What happens if you find a treasure? Situation n.1 : if you find a treasure in someone else's house According to the French law, the value of the treasure must be shared between the person who found it and the owner of the house. For example, in 2016, workers who were repairing a fireplace (chimney?) discovered behind it a box in copper. They shook it and discovered 600 coins dating from 1870. Those coins were valued up to 100, 000 euros. The justice decided that the amount of money should be shared equally between the workers and the owner of the house. Situation n.2 : A treasure at home If you find a treasure while gardening, it belongs to you. You have the right to keep it unless it has an archeological value. Situation n.3 : A treasure at home with an archeological value If it has an archeological value, you must call the authorities. They will have the right to keep your discovery for five years maximum and in the end, they can offer to buy it to you (or you can keep it if you refuse). Situation n.4 : Using a metal detector If you use a metal detector, the law considers that it is not a discovery "per chance" and you'll have to give what you have found to the authorities. If you don't, and if the authorities discover you kept this teasure for you, you'll risk to pay a huge fine. Situation n.5 : .... and if I find some petrol? The state will take your property claiming that it is its. You'll have but no choice to leave your property. I have never found a treasure. The only things we found at home, in the garden, were old horshoes and rusty irons...