5TC37F3: Although Calcite is a common species, that does not always hold true globally. This is a novelty for Madagascar since its discovery in August 2004, an aggregate that highlights the sharpness of its crystals, their color and luster and, especially, the appearance of extraordinarily unusual twins formed by the interpenetration of two rhombohedra.
Basalt Quarry, Ambariomiambana, Sambava District, Sava Region  Madagascar (08/2004)

Specimen size: 5.2 × 3.3 × 2.3 cm = 2.05”

Main crystal size: 2.6 × 1.7 cm = 1.02”