A lump of silver has been discovered in the Eden Valley of the UK NW Region. The weight is approx 400 grammes and the shape is rounded and irregular - a pebble. Markings are inscribed on the lump - "R07M". Any suggestions about the meaning of the characters? A supplementary question is what do we know about the shape and weight of 19th century silver ingots? ( if Ingots be the right description) Thanks