Where it forms, where it's found
Physical
- Colour
- blue to blue–violet color
Cause of the color can be attributed to the charge transfer between Fe2+ on the octahedron and Fe3+ in the edge-shared T11 tetrahedra in the iolite. (1)The color coordinates a* and b* were the main factors affecting the variation of the chroma C*. (2)Fe is mainly present as Fe2+ and controls the lightness L* and the hue angle h°, while Mn does not have a significant effect on the color of iolite. (3)The intervalence charge transfer between Fe2+ and Fe3+ is responsible for the blue color of iolite. (4)The color parameters of iolite are affected by the change of light sources, and the hue angle h° is the most affected.
Optical
- Pleochroism
- Strong
blue–violet iolite shows light purple, dark purple and yellow–brown pleochroism; blue iolite shows colorless to yellow, blue–gray and dark purple pleochroism
Chemical composition
Literature, links & citation
- 1807Werner, A. G. (1807)
- 2022Liu, Xin, Guo, Ying (2022) Study on the Color-Influencing Factors of Blue Iolite. Minerals, 12 (11) 1356 doi:10.3390/min12111356 DOI: 10.3390/min12111356
@misc{mineral2026,
author = {Mineral Index editorial board},
title = {Iolite — Mineral Index},
year = {2026},
url = {https://mineralindex.org/minerals/iolite-5119},
note = {Accessed 2026-05-11}
}