Inherited these pans. My mom always said they were decorative only. Not for cooking. She had them displayed on the wall in the kitchen. How do I know for sure if they're safe or not? These seem very light weight and single ply on the bottoms ( unlike my Calphalon stainless). Lined with tin perhaps? "Made in Portugal". I currently have an induction range. And know nothing about copper cookware. Advice gratefully received. Thanks all!