Adachiite

Adachiite (CaFe₃Al₆(Si₅AlO₁₈)(BO₃)₃(OH)₃(OH)) is a brownish–purple to bluish–purple mineral, discovered in 2013 and described in 2014.^[1]

Adachiite
General
Category	Tourmaline Group
Formula	CaFe3Al6(Si5AlO18)(BO3)3(OH)3(OH)
IMA symbol	Adc
Strunz classification	9.CK.
Crystal system	Trigonal
Crystal class	3m - Ditrigonal Pyramidal
Unit cell	1578.39 ų
Identification
Color	Brownish–purple to bluish–purple
Specific gravity	3.228
Density	3.228 g/cm3
Birefringence	δ = 0.030
Pleochroism	Strong

It is named for Tomio Adachi, an amateur geologist and retired teacher who performed many investigations in and around the Kiura Mine and inspiration to many local children who would go on to become professional mineralogists.

Its type locality is the Kiura Mine in Ōita Prefecture, Japan.^[2]