Adachiite
A purple tourmaline-group mineral from Japan's Kiura mine, named for Tomio Adachi, a local teacher and amateur geologist.
Intro adapted from Wikipedia (CC BY-SA).
Adachiite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaFe²⁺₃Al₆(Si₅AlO₁₈)(BO₃)₃(OH)₃(OH).
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Tourmaline structural group.
Key properties: Mohs hardness 7; specific gravity 3.228; optically uniaxial.
IMA symbol Adc, IMA status: approved, named in 2012.
Found in a hydrothermal vein that cuts a lateritic metamorphic emery (corundum and hercynite) deposit.
It is found associated with Margarite, chlorite, diaspore, schorl.
The mineral was named to honor Tomio Adachi (b. 1923), an amateur mineralogist.