Sonolite

Sonolite
Sonolite (in bottom left corner) with zincite and manganosite
General
Category	Silicate minerals
Formula (repeating unit)	Mn9(SiO4)4(OH,F)2
IMA symbol	Snl[1]
Strunz classification	9.AF.55
Dana classification	52.3.2d.3
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/b[2]
Unit cell	a = 4.87 Å, b = 10.66 Å c = 14.28 Å β = 100.3°, Z = 2[2]
Identification
Color	Red-orange, pinkish brown to dark brown Colorless in thin section[2]
Twinning	Common, singular or lamellar on {101}[2]
Mohs scale hardness	5.5
Luster	Vitreous, dull
Diaphaneity	Transparent to translucent[3]
Density	3.82–4.00 (measured)[2]
Optical properties	Biaxial (−)
Refractive index	nα = 1.765 nβ = 1.778 nγ = 1.787
Birefringence	δ = 0.022
2V angle	75° to 82° (measured)
Dispersion	r > v[2]
References	[4]

Sonolite is a mineral with formula Mn₉(SiO₄)₄(OH,F)₂. The mineral was discovered in 1960 in the Sono mine in Kyoto Prefecture, Japan. In 1963, it was identified as a new mineral and named after the Sono mine.