Suanite

Suanite is a magnesium borate mineral with formula Mg₂B₂O₅.

Suanite
General
Category	Borate mineral
Formula	Mg2B2O5
Strunz classification	6.BA.05
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Unit cell	a = 12.31 Å, b = 3.12 Å c = 9.2 Å; β = 104.33°
Identification
Color	White to pale gray
Crystal habit	Clusters of prismatic to fibrous crystals
Cleavage	Perfect parallel to {010}
Mohs scale hardness	5.5
Luster	Silky to pearly
Streak	White
Diaphaneity	Translucent
Specific gravity	2.91
Optical properties	Biaxial (–)
Refractive index	nα = 1.596 nβ = 1.639 nγ = 1.670
Birefringence	δ = 0.074
2V angle	70°
References	[1][2][3]

It was first described in 1953 by Japanese scientist Takeo Watanabe from the University of Tokyo.^[4] His first contact with the mineral was during analysis of gold- and copper- bearing skarn minerals from the Hol Kol mine, located in North Korea obtained in 1939. Due to the small sample size available to him, he was only able to determine the unknown substance's optical properties under a microscope. Watanabe was able to return to the site in 1943 and obtain further samples that permitted him to perform chemical analysis on the material.^[4]