Based on its appearance in the field, the substance was initially thought to be molybdenite (the mineral from which Re was first extracted), but after analysis back in the laboratory it was found ...
Molybdenite (Molybdenum Disulphide); (7) Galena (Lead Sulphide); (8) Carborundum (Artificial Silicon Carbide) . The Electrolytic Detector, perhaps the most widely known type, appears in many forms ...