Chocolate Calcite and brown aragonite are essentially the same material in terms of composition and are often sold interchangeably, though they are technically different structural polymorphs. Chocolate Calcite is a trade name for a banded, brown, often fibrous, variety of calcium carbonate found in Mexico and Pakistan. It is scientifically categorized as aragonite, or sometimes a mixture, that forms in different, higher-pressure conditions than typical calcite.
The same holds for other colors of calcite and aragonite.
