Silicon also is a commonly used alloy in iron, steel, and aluminum

This electrician I worked with many years ago grew up in a very rural area. In the late 30's they were making what is referred to as non powered crystal radio by winding wires from old coils around oatmeal boxes and getting these gray shiny crystalline rocks from along the C&O railroad tracks to make their detector out of. You moved the tickler wire from the coil around on that gray shiny rock until a radio station started coming in. They had made a silicon diode detector and didn't know it?