Sonolite

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.

Sonolite
Sonolite (in bottom left corner) with zincite and manganosite
General
Category	Silicate minerals
Formula	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]

Description

Sonolite is transparent to translucent^[3] and is red-orange, pinkish brown to dark brown in color and colorless in thin sections. The mineral has a granular habit or occurs as prismatic to anhedral crystals up to 2.5 cm (0.98 in).^[2] Sonolite is the manganese analogue of clinohumite,^[5] a dimorph of jerrygibbsite,^[2] and a member of the humite group.^[4]

The mineral occurs in metamorphosed manganese-rich deposits. Sonolite has been found in association with calcite, chlorite, franklinite, galaxite, manganosite, pyrochroite, rhodochrosite, tephroite, willemite, and zincite.^[2]

History

In 1960, Mayumi Yoshinaga was investigating alleghanyite and other manganese orthosilicates in Japan. He discovered a dull, red-brown mineral on the first level ore body of the Sono Mine, and later from a number of other sites.^[5] Using samples from ten locations in Japan and one in Taiwan, the mineral was described in 1963 and identified as a new mineral species.^[6] It was named sonolite after the mine in which it was first found and the name was approved by the International Mineralogical Association.^[4][5]

Distribution

As of 2012^[update], sonolite has been found in Austria, France, Japan, Kyrgyzstan, Romania, Russia, Sweden, Switzerland, Taiwan, and the United States.^[4] The type material is held at Harvard University in Cambridge, Massachusetts, US.^[2]