Which of the following is NOT a common method of metal identification?

• A. Color
• B. Fractured surface
• C. Electrical conductivity
• D. Weight

Answer: (C)

Metal identification relies on observable or easily measured traits. Color can give a quick clue, as some metals and coatings show distinctive hues. Examining a fractured surface reveals how a metal breaks and its microstructure, which helps tell apart metals like steel, aluminum, or cast iron. Weight or density is another practical clue because metals have characteristic masses for a given size, so heft can point toward a specific material. Electrical conductivity isn’t a common quick ID method because many metals have overlapping conductivity ranges, and obtaining an accurate measurement needs specialized equipment and controlled conditions. All of this makes conductivity less reliable for general identification than color cues, fracture characteristics, or density.