Calcite vs. Aragonite — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Updated on September 22, 2023
Calcite and Aragonite are both forms of calcium carbonate (CaCO3), but they differ in structure, stability, and occurrence. Calcite is more stable and abundant, while Aragonite is less stable and occurs in specific environments.
Difference Between Calcite and Aragonite
Table of Contents
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Key Differences
Calcite and Aragonite are two distinct mineral forms of calcium carbonate. Calcite is the most common and abundant form of calcium carbonate and can be found in various geological settings. It is the principal component of limestone and marble, forming in environments that range from the bottom of the ocean to hot springs.
Aragonite, on the other hand, is a less common form of calcium carbonate. It is typically found in more specific conditions like high-pressure mineral deposits or biological formations like coral reefs and shells. Aragonite is more soluble and denser than Calcite, which makes it less stable over geological timescales.
Both Calcite and Aragonite have different crystalline structures. Calcite forms trigonal crystals, which are more stable and less soluble in water compared to Aragonite. Aragonite has an orthorhombic crystal system, which results in needle-like crystals that are more tightly packed than those of Calcite.
These different structures also lead to different physical properties. Calcite, for example, has a lower density and is less hard than Aragonite. The different crystal structures also contribute to variations in the way each mineral interacts with light, affecting properties like birefringence and hardness.
Chemically speaking, both Calcite and Aragonite are the same; they consist of calcium, carbon, and oxygen arranged in a calcium carbonate molecule. However, their different structures lead to different reactions with acids and bases, affecting their behavior in chemical processes.
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Comparison Chart
Stability
More stable
Less stable
Occurrence
Widespread
Specific conditions like coral reefs
Crystal Structure
Trigonal
Orthorhombic
Solubility
Less soluble
More soluble
Density
Lower density
Higher density
Compare with Definitions
Calcite
Most common form of calcium carbonate.
Calcite is abundant in limestone deposits.
Aragonite
Forms orthorhombic crystals.
The aragonite crystal had a needle-like, orthorhombic structure.
Calcite
Less soluble in water.
Calcite takes longer to dissolve in water compared to Aragonite.
Aragonite
Less common form of calcium carbonate.
Aragonite is often found in coral reefs.
Calcite
Principal component of limestone and marble.
The beautiful marble is mainly composed of calcite.
Aragonite
Found in specific environments.
Aragonite occurs in high-pressure mineral deposits.
Calcite
Forms trigonal crystals.
The calcite crystal showed a distinct trigonal shape.
Aragonite
More soluble in water.
Aragonite dissolves more easily in water compared to Calcite.
Calcite
Lower density compared to Aragonite.
Calcite is lighter and less dense than Aragonite.
Aragonite
Higher density compared to Calcite.
Aragonite is denser than Calcite.
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as "calcite".
Aragonite
Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, CaCO3 (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including precipitation from marine and freshwater environments.
Calcite
A common crystalline form of natural calcium carbonate, CaCO3, that is the basic constituent of limestone, marble, and chalk. Also called calcspar.
Aragonite
An orthorhombic mineral form of crystalline calcium carbonate, dimorphic with calcite.
Calcite
(mineral) a very widely distributed crystalline form of calcium carbonate, CaCO3, found as limestone, chalk and marble
Aragonite
(mineral) An evaporite consisting of anhydrous calcium carbonate with the chemical formula CaCO3; it is dimorphous with calcite.
Calcite
Calcium carbonate, or carbonate of lime. It is rhombohedral in its crystallization, and thus distinguished from aragonite. It includes common limestone, chalk, and marble. Called also calc-spar and calcareous spar.
Aragonite
A mineral identical in composition with calcite or carbonate of lime, but differing from it in its crystalline form and some of its physical characters.
Calcite
A common mineral consisting of crystallized calcium carbonate; a major constituent of limestone
Aragonite
A mineral form of crystalline calcium carbonate; dimorphic with calcite
Common Curiosities
What is the crystal structure of Calcite?
Calcite has a trigonal crystal structure.
Which is more stable, Calcite or Aragonite?
Calcite is more stable over geological timescales.
What is the crystal structure of Aragonite?
Aragonite has an orthorhombic crystal structure.
Is Calcite soluble in water?
Calcite is less soluble in water compared to Aragonite.
Is Aragonite found in coral reefs?
Yes, Aragonite is commonly found in coral reefs and shells.
Is Calcite found in marble?
Yes, it's a principal component of marble.
Can Aragonite convert to Calcite?
Yes, Aragonite can convert to Calcite over time.
Do Calcite and Aragonite have the same chemical formula?
Yes, both have the formula CaCO3.
Are Calcite and Aragonite the same?
No, they are different forms of calcium carbonate with different structures and properties.
Is Calcite more common than Aragonite?
Yes, Calcite is more abundant and widespread.
Which has a higher density, Calcite or Aragonite?
Aragonite has a higher density.
How do Calcite and Aragonite react to acids?
Both react with acids but at different rates due to their solubility.
Which is harder, Calcite or Aragonite?
Aragonite is harder than Calcite.
Can Calcite and Aragonite coexist?
They can coexist but usually form under different conditions.
Are Calcite and Aragonite used in industry?
Yes, both are used but Calcite is more commonly used due to its abundance.
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Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
