The names of ferrous metals and nonferrous metals often lead people to misunderstand that ferrous metals must be black, but they are not.
Some junior and senior high school textbooks define ferrous metals and nonferrous metals in this way: ferrous metals include iron, manganese, chromium, and other metals are called nonferrous metals.
Related reading: Ferrous vs Non-ferrous Metals: What’s Their Difference?
Obviously, iron, manganese and chromium are not black.
Pure iron is silver white; Chromium is silver white; Manganese is off white.
Then why are they considered as ferrous metals?
In fact, the parts and tools produced by iron and iron alloys in industry cannot guarantee the specular reflection of light on their surfaces because their surfaces are not smooth enough.
They absorb part of the light length and cause the surface darkening, which is commonly referred to as diffuse reflection.
Therefore, in the traditional sense, all metal materials such as iron and iron alloys are called ferrous metals, and iron alloys are often mixed with manganese and chromium.
Naturally, manganese and chromium are also called ferrous metals.
Black iron powder used in physical experiments
In foreign literature, ferrous metals and nonferrous metals use these two words:
Ferrous metal and non ferrous metal are very interesting.
Here, “ferrous” means “containing iron”.
I think you can understand it better.
The full name of ferrous metal is “ferrous metal material”, which refers to various metal materials containing iron, collectively referred to as pig iron or steel of ferroalloy;
Non ferrous metals are all metal materials that do not contain iron or are not iron.