Are Nobel medals cast or struck?

Irving Wallace wrote a book called The Prize in 1961 - a speed reader may well discover in it the answer to the cast/struck question. It's only 755 pages and seems to contain all other trivia related to the presentation!

Nobel prize medals, at least those for medicine or physiology, for chemistry, for physics, and for literature, are, or at least were, definitely struck from dies in the usual way. I've held one in my hands (that of Albert Szent Gyorgyi, for medicine or physiology, issue in 1930, which is housed at the Semmelweis Museum in Budapest). I also owned bronze offstrikes in bronze but, alas, these were stolen in transit.