Home > Mexico III Ojuela I – January 12 > MS1717 Aragonite


Aragonite is calcium carbonate, polymorphous with calcite. Under room conditions, calcite is more stable than aragonite. Calcite transforms to aragonite with the application of pressure; aragonite is denser than calcite. The mineral name recalls its discovery in Aragon, Spain (Haüy, 1791). The host rock at Ojuela is limestone, consisting of calcite, and aragonite forms by re-deposition mediated biologically.

This is a shell of calcite, lined with 1-2 mm rhombohedral calcite crystals, on which elongate aragonite crystals have grown. The aragonite crystals are colorless and transparent, reaching 1.6 cm long. Some of the aragonite crystals have broken at their bases. Rare from Ojuela. This specimen was part of the Charles Trantham (1936-2020) estate.

Price: $85

Item code: MS1717

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