Which of the following statements about mineral resources is incorrect?

Iron ores are graded chiefly by their iron (Fe) content and magnetic quality — Magnetite is rated the finest iron ore, with iron content reaching up to about 70%, while Hematite, though the most heavily mined iron ore in India, carries a comparatively lower iron content of roughly 50–60%. Separately, metallic minerals split into Ferrous minerals (iron-bearing, e.g. iron ore, manganese, chromite) and Non-Ferrous minerals (iron-free, e.g. copper, bauxite, tin, lead, zinc); "non-ferrous mineral" is the standard term used for tin in Indian mineral-resource classification.

Checking each statement against this:

• Copper — ductile and a good conductor of electricity is an accurate, well-known property; no error here.

• Aluminium/Bauxite — aluminium is indeed extracted from the clay-like ore bauxite (Bayer process followed by electrolysis); accurate.

• Tin — calling it a non-ferrous mineral matches the standard Ferrous/Non-Ferrous classification used for Indian mineral resources; accurate, not an error.

• Hematite — described here as “the finest iron ore … up to 70 percent” iron — that description belongs to Magnetite. Hematite's iron content is lower, around 50-60%, so this statement is the error.

NCERT's Class X Geography chapter on minerals makes the same distinction explicitly: “Magnetite is the finest iron ore with a very high content of iron up to 70 per cent… Hematite ore is the most important industrial iron ore in terms of the quantity used, but has a slightly lower iron content than magnetite (50-60 per cent).”

So the statement about Hematite being the finest iron ore with up to 70% iron is the incorrect one among the four — that description fits Magnetite.