Katayamalite
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| Katayamalite | |
|---|---|
 | |
| General | |
| Category | Minerals |
| Formula | KLi3Ca7Ti2(SiO3)12(OH)2 |
| IMA symbol | Kyl[1] |
| Strunz classification | 9.CJ.25 |
| Dana classification | 61.01.04.02 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic H-M symbol: 2/m |
| Space group | B2/b |
| Unit cell | 3,179.12 |
| Identification | |
| Color | White |
| Crystal habit | Tabular, common twinning |
| Cleavage | Perfect on {001} |
| Mohs scale hardness | 3.5 - 4 |
| Luster | Vitreous, pearly |
| Streak | White |
| Density | 2.91 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.670 nβ = 1.671 nγ = 1.677 |
| 2V angle | Measured: 32 Calculated: 46 |
| Dispersion | Strong r > v |
| Ultraviolet fluorescence | brilliant blue-white under SW |
| Other characteristics |  Radioactive |
Katayamalite is a cyclosilicate mineral that was named in honor of mineralogist and professor Nobuo Katayama. It was approved in 1982 by the International Mineralogical Association, and was first published a year later.[2]
Katayamalite is the hydroxyl analogue of baratovite and the hydroxyl end member of the series,[3] but was first described as a fluor-dominant mineral. Some scientists claim it to be rather hydroxyl- than fluor dominant, which would make baratovite isostructural with it. It would make the two minerals the same species, with baratovite having priority. As the case hadn't been clarified, katayamalite remains an IMA-approved mineral until this day.[2]