Rock identification for cement raw materials: which rock in the list is NOT calcareous (i.e., not primarily composed of calcium carbonate)?

Introduction / Context:
Calcareous rocks provide the CaCO3 needed for cement manufacture and for lime production. Distinguishing calcareous from non-calcareous formations is a basic geology skill relevant to quarry selection and raw mix design.

Given Data / Assumptions:

• Limestone, marl, and chalk are classic calcareous rocks.
• Laterite is an iron- and aluminium-rich weathering product formed in tropical climates.
• “Calcareous” implies high calcium carbonate content.

Concept / Approach:
Limestone and chalk are predominantly CaCO3; marl is a calcareous clay rich in carbonates. Laterite, by contrast, is rich in Fe/Al oxides/hydroxides, often low in CaCO3, and used more as an iron/alumina corrective rather than as a calcareous base.

Step-by-Step Solution:
Compare compositions: limestone/chalk/marl → CaCO3-rich; laterite → Fe/Al-rich.Select the rock that is not calcareous: laterite.

Verification / Alternative check:
Mineralogical descriptions confirm laterite’s predominance of goethite/hematite/gibbsite rather than carbonates.

Why Other Options Are Wrong:

• Limestone/Chalk/Marl: all calcareous; principal calcareous raw materials in cement.
• None of these: incorrect because laterite clearly stands apart.

Common Pitfalls:
Confusing marl (calcareous clay) with purely argillaceous sediments; assuming any sedimentary rock is calcareous.

Final Answer:
Laterite