What is the ruling on gold found on a beach, if one does not trust the officials in charge of the place and fears aggression from them if the find is reported to them?

If you do not trust the integrity of those in charge of the beach, then do not pay them the piece of gold you found. The ruling regarding this found item is that you should know its characteristics and publicize it for a year, without mentioning its specific features, using means that ensure the announcement reaches the largest number of people, such as: placing an advertisement on the beach or in nearby areas, or publishing an advertisement on social media. If its owner comes and describes it, then hand it over to him. If its owner does not come after a year, then you may benefit from it or donate it as charity. If its owner comes after that, then hand it over to him if it is still available; otherwise, pay its value.