My wife and I have found what appears VISUALLY to be a 1760 Maria Theresia Austrian Thaler. The problem is that it weighs less than 6 grams (alloy) and the research says it should weigh about 28 grams (silver). All dimensions, inscriptions and artwork appear authentic. It's beautifully made in the tiniest detail and I think it must have been produced with Austrian mint approval. Could anyone help us identify just what it is or when/where it might have been made.