The Oriented Transformation of Aragonite into Calcite

D. R. Dasgupta
Senior Mineralogist, Geological Survey of India, 29 Chowringhee, Calcutta 16, India

Summary: The oriented transformation of aragonite to calcite has been studied by X-rays. The [100], [110], and [001] directions ofaragonite become [101¯0], [011¯0], and [0001] of calcite. The transformation was completed by a re-orientation of the CO3 groups about the [001] direction of aragonite through an angle of 30°, different rows of CO3 being turned in opposite directions, together with a displacement along the same direction. The layers of Ca ions also are shifted along the basal plane of calcite so that their arrangement perpendicular to the [0001] direction of calcite becomes ABCABCA… instead of ABABABA… as in aragonite.

Mineralogical Magazine; June 1964 v. 33; no. 265; p. 924-928; DOI: 10.1180/minmag.1964.033.265.09
© 1964, The Mineralogical Society
Mineralogical Society (