Mineralogy quick fact: What is the typical specific gravity (Gs) of the mineral Calcite commonly encountered in carbonate rocks?

Introduction / Context:
Specific gravity of minerals is useful for identifying constituents of aggregates and rock cores. Calcite (CaCO3) is the principal mineral in limestones and many cementitious fillers. Knowing its Gs helps in density and mix proportion calculations.

Given Data / Assumptions:

• Standard laboratory values at room temperature and pressure.
• Natural variability may occur due to impurities.

Concept / Approach:
Calcite’s specific gravity typically lies close to 2.71–2.72. By contrast, quartz is about 2.65, dolomite about 2.85, and heavier minerals (e.g., magnetite) are much higher. Selecting the closest listed value differentiates calcite from quartz and dolomite in routine identification.

Step-by-Step Solution:

Verification / Alternative check:
Handbooks of mineralogy and concrete aggregates list calcite specific gravity near 2.71–2.72; petrographic tests corroborate.

Why Other Options Are Wrong:

• 2.65 corresponds to quartz.
• 2.85 is closer to dolomite (CaMg(CO3)2).
• 2.90 and 3.10 exceed typical calcite values.

Common Pitfalls:
Confusing calcite with quartz due to similar appearance; ignoring the effect of impurities on measured Gs.

Final Answer:
2.72