Among common minerals, which one is recognized as the principal ore of uranium used for industrial extraction?

Introduction / Context:
Identifying the principal uranium ore is a fundamental piece of nuclear fuel-cycle knowledge. The mineralogical source affects beneficiation, leaching routes, and downstream refining steps. This question tests recognition of the primary uranium-bearing mineral used globally.

Given Data / Assumptions:

• Industrial-scale uranium extraction context.
• Typical mineralogy and naming conventions.
• Comparison with ores of other metals for contrast.

Concept / Approach:
Pitchblende, also known as uraninite, is a uranium oxide mineral (commonly approximated as UO2 with U3O8 components) and is the most important source of uranium. While monazite may contain trace uranium, it is best known for rare earths and thorium. Cassiterite is tin ore (SnO2), and chalcopyrite is copper–iron sulfide (CuFeS2), neither relevant for uranium production.

Step-by-Step Solution:
List candidates: pitchblende, monazite, cassiterite, chalcopyrite.Match each to its metal: pitchblende → uranium; monazite → rare earths/thorium; cassiterite → tin; chalcopyrite → copper.Select the principal uranium ore: pitchblende (uraninite).

Verification / Alternative check:
Historical mining districts and modern operations alike cite uraninite/pitchblende as the dominant uranium ore, supplying feed to milling and hydrometallurgical circuits that produce yellowcake (U3O8).

Why Other Options Are Wrong:
Monazite: mainly rare earths and thorium, not the principal uranium source.Cassiterite: tin ore, unrelated to uranium.Chalcopyrite: copper ore.Ilmenite: iron–titanium oxide (TiO2 feed), not uranium.

Common Pitfalls:
Equating trace uranium presence with principal ore status.Confusing ore names across different metals due to similar-sounding minerals.

Final Answer:
Pitchblende (uraninite)