After Henri Becquerel discovered that uranium rays could pass through metal, Marie Curie decided she wanted to research it. She specifically wanted to use it as the subject of her thesis. Many thought she would never be able to finish her thesis because she was, as quoted from Rockwell, “...a frail young wife and new mother,” still she persisted. She started her research in early 1898, during her time studying it she discovered that pitchblende, minerals found in uranium, held the same effects that uranium had although superior than the latter. By the summer of that same year Pierre decided to join her in her research. ​​​​​​​