Geology for Engineers – Limestones as a Rock Class Limestones encountered in building stone quarries and cement raw mixes are generally classified as which type(s) of rocks based on their origin and structure?

Introduction:
Limestone is a cornerstone raw material in construction and cement manufacturing. Knowing its rock classification helps in assessing quarrying behavior, bedding, and variability in composition and durability.

Given Data / Assumptions:

• Limestone commonly forms by chemical/biochemical precipitation of calcium carbonate in aqueous environments.
• It is a sedimentary rock by genesis.
• It typically exhibits bedding planes, hence is stratified.

Concept / Approach:

The terms “aqueous,” “sedimentary,” and “stratified” are not mutually exclusive. They describe, respectively, the depositional medium, genetic class, and structural arrangement of layers. Most limestones therefore qualify under all three descriptors, although metamorphosed limestone becomes marble and is then metamorphic.

Step-by-Step Solution:

Verification / Alternative check:

Engineering geology texts consistently list limestone under sedimentary, stratified, and aqueous categories, reserving “metamorphic” for marble after recrystallization.

Why Other Options Are Wrong:

Metamorphic classification applies only after metamorphism (marble), not to ordinary limestone beds used as building stone.

Common Pitfalls:

Thinking each term is exclusive; overlooking that depositional environment and structure descriptors can all apply simultaneously.

Final Answer:

All of the above descriptions are applicable