Publication Date:
2015-07-03
Description:
Imayoshiite, Ca 3 Al(CO 3 )[B(OH) 4 ](OH) 6 ·12H 2 O, occurs in cavities in the altered gabbro xenolith in the sepentinized dunite exposed at Suisho-dani, Ise City, Mie Prefecture, Japan. Imayoshiite is colourless and transparent with a vitreous lustre and its aggregates are white with a silky lustre. Imayoshiite has a white streak. Its Mohs hardness is 2–3. It is brittle, the cleavage is distinct on {100} and the fracture is uneven. The mineral is uniaxial (–) with the indices of refraction = 1.497(2) and = 1.470(2) in white light. Imayoshiite is hexagonal, P 6 3 , a = 11.0264(11), c = 10.6052(16) Å by powder diffraction and a = 11.04592(2), c = 10.61502(19) Å by single-crystal diffraction. The structural refinement converged to R 1 = 2.35%. Imayoshiite is the first member of the ettringite group with both CO 3 and B(OH) 4 anions.
Print ISSN:
0026-461X
Electronic ISSN:
1471-8022
Topics:
Geosciences