(d) Nickel
Nickel is a ferrous mineral. Copper and tin are non-ferrous metals, and bauxite is an ore of aluminium (also non-ferrous).
Source: Chapter 5, Ferrous Minerals & Non-Ferrous Minerals sections.
---
The textbook classifies ferrous minerals as those containing iron or used in iron/steel production (iron ore, manganese, nickel). Copper, tin, and bauxite are explicitly listed or implied as non-ferrous. Examiners expect students to recall this classification directly. Note: bauxite is an ore (not a metal), and copper is clearly non-ferrous per the chapter.