Home > American Minerals IV – August 26 > MS1646 Aragonite (single crystal from California)

Aragonite (single crystal from California)


Aragonite is calcium carbonate, polymorphous with calcite. Calcite transforms to aragonite with the application of pressure, and aragonite has a higher density than calcite. Aragonite has orthorhombic symmetry, coincidentially with nearly hexagonal unit cell metrics. Consequently, aragonite readily twins by rotation about its c axis. The mineral name denotes its discovery in Aragon, Spain Haüy (1791).

A 1.9 by 0.8 cm untwinned aragonite lies flat, parallel to but somewhat lifted off a serpentine matrix. This specimen was part of the Charles Trantham (1936-2020) estate. A small handwritten note indicates that Trantham self-collected this specimen in 1966.

Price: $75

Item code: MS1646

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