Inderite

Inderite, also known as lesserite, is a mineral that was named after its source, the Inder lake, near the Inder Mountains in Kazakhstan.^[2] The samples were described in English by the soviet mineralogist Boldyreva in 1937. It is a rare secondary mineral but common in salt, potassium and borate deposits.

Inderite
General
Category	Minerals
Formula	MgB3O3(OH)5 · 5H2O
IMA symbol	Idr[1]
Strunz classification	6.CA.15
Dana classification	26.3.1.3
Crystal system	Monoclinic
Crystal class	Prismatic (2/m)
Space group	P21/b
Unit cell	1,041.64 ų
Identification
Formula mass	279.85
Color	Colorless, white, pink; colorless in transmitted light
Cleavage	Perfect on {010}, on {110} good
Fracture	Uneven
Mohs scale hardness	2.5 – 3
Luster	Vitreous, greasy, pearly, dull
Diaphaneity	Transparent, translucent
Density	1.8
Optical properties	Biaxial (+)
Refractive index	nα = 1.488 nβ = 1.491 nγ = 1.505
Birefringence	0.017
Pleochroism	None
2V angle	Measured 37°, calculated 52°
Dispersion	Weak, r > v
Ultraviolet fluorescence	None
Solubility	Soluble in hydrochloric acid
Other characteristics	Pearly on cleavages

Crystallography

Inderite is a member of the inderite group, and a dimorph of kurnakovite.^[3] It contains boron, hydrogen, magnesium, and oxygen. It can form continuous layers. Deposits include Argentina, China, Italy, Kazakhstan, Russia, Turkey, and the US. It contains 8.69% magnesium, 11.59% boron, 5.40% hydrogen and 74.32% oxygen.

Usage

Inderite is one of the natural borates commonly used in the chemical industry. This hydrated neotriborate is still used in iron metallurgy. It is also used in gemology despite its qualities. Since inderite is very soft, it is hard to cut, but sometimes a cabochon cut is possible. There are many cuttable sized specimens, and although there are only a few mines containing inderite, it is not considered a great rarity. After cutting, inderite's surface can become white and cloudy, hence why it needs to be dried and properly stored after cutting.^[4] It is cleaned with water after cutting as it is insoluble in water, but can be dissolved in hydrochloric acid.