Complex sentence: Professor A. Kahma and T. Mustonen wondered in spring 1962 whether dogs could smell a rock containing sulphide ore, they, as most geologists world wide, had noticed, that sulphides give an odor especially when broken.
Split into simpler sentences: Professor A. Kahma and T. Mustonen had wondered in spring 1962 whether dogs could smell a rock containing sulphide ore. They had noticed that sulphides give an odor especially when broken.