What is the Difference Between Calcite and Aragonite?

Calcite and aragonite are both forms of calcium carbonate (CaCO3) and are considered polymorphs, meaning they have the same chemical composition but different crystal structures. The key difference between the two is their crystal systems: calcite has a trigonal crystal system, while aragonite has an orthorhombic crystal system.

Some other differences between calcite and aragonite include:

• Stability: Calcite is more stable than aragonite, which is metastable and can transform into calcite over time or when heated.
• Hardness: Aragonite has a higher hardness than calcite, ranging from 3.5 to 4 on the Moh's scale, while calcite has a hardness of 3.
• Rarity: Aragonite is rarer than calcite.
• Color: Aragonite can commonly be green, while calcite can be red.
• Luster: Aragonite can be dull or resinous, while calcite can be vitreous or pearly.

Both minerals are widely found in nature and have various applications in society, such as in medicine, animal feed, and construction materials. They are commonly used by invertebrate organisms to construct their shells and hard parts.

Comparative Table: Calcite vs Aragonite

Here is a table summarizing the differences and similarities between calcite and aragonite:

Both calcite and aragonite are polymorphs of calcium carbonate, meaning they have the same chemical composition but different crystal structures. They can both be found in various settings, including sedimentary rocks and marine organisms.