Uranium ore knowledge check: among the common uranium-bearing minerals listed, which one typically contains the highest percentage of uranium by composition?

Introduction / Context:
Identifying uranium-rich minerals is important in mining, fuel-cycle planning, and general science GK. Different ores vary widely in uranium concentration and in the presence of other actinides or rare-earth elements.

Given Data / Assumptions:

• We compare representative uranium-bearing minerals.
• We seek the ore with the highest typical uranium percentage.
• Names may refer to mineral groups (e.g., uraninite/pitchblende) rather than strict chemical formulas.

Concept / Approach:
Pitchblende (also known as uraninite) is essentially uranium dioxide-rich mineral and is historically the most uranium-dense ore, often the primary source in high-grade deposits. Carnotite is a potassium–uranium–vanadium mineral with lower U content. Monazite sands are largely rare-earth phosphates with thorium and only modest uranium traces. Thorite is primarily a thorium mineral. “Rescolite” is not a standard uranium ore name in typical mining catalogs and may represent a distractor or misnomer.

Step-by-Step Solution:
Recall mineral compositions: uraninite (UO2±x) is highly uranium-rich.Compare with carnotite and monazite: uranium present but at lower percentages.Exclude thorium-dominant minerals (thorite) and nonstandard names.Select pitchblende/uraninite as the richest uranium ore.

Verification / Alternative check:
Historical mining records and geochemical references consistently cite high-grade uraninite/pitchblende veins as the most uranium-concentrated mineralized material used in extraction.

Why Other Options Are Wrong:
Carnotite: Uranium present but diluted by K and V components.Thorite: Predominantly thorium; not a high-U mineral.Rescolite: Not a recognized primary uranium ore.Monazite: Rare-earth phosphate with thorium; uranium is minor.

Common Pitfalls:
Assuming any actinide-bearing sand (monazite) is uranium-rich; many are thorium-dominant. Always match mineral identity with its primary actinide content.

Final Answer:
Pitchblende (uraninite)