Home > American Minerals IV – August 26 > MS1646 Aragonite (single crystal from California)
Aragonite (single crystal from California) - Sold
- Berkeley Hills tunnel
- Oakland
- Alameda County
- California
- U.S.A.
- 5.8 by 4.9 by 2.2 cm – Miniature specimen (fits into a 5 cm cube)
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.
