Kernite

Kernite
General
Category	Inoborates
Formula (repeating unit)	Na 2B 4O 6(OH) 2·3H 2O
IMA symbol	Ker[1]
Strunz classification	6.DB.05
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/c
Unit cell	a = 7.0172(2) b = 9.1582(2) c = 15.6774(5) [Å] β = 108.861(2)°; Z = 4
Identification
Formula mass	273.22 g/mol
Color	Colorless, white
Crystal habit	Crystalline - occurs as well-formed coarse sized crystals
Cleavage	Perfect on [100] and [001], good on [201]
Fracture	Splintery
Tenacity	Brittle
Mohs scale hardness	2.5-3
Luster	Vitreous - pearly
Streak	White
Specific gravity	1.9 - 1.92
Optical properties	Biaxial (-)
Refractive index	nα=1.454, nβ=1.472, nγ=1.488
Birefringence	δ =0.0340
2V angle	80°
Other characteristics	Non-radioactive, non-fluorescent, non-magnetic
References	[2][3][4]

Kernite, also known as rasorite, is a hydrated sodium borate hydroxide mineral with formula Na
₂B
₄O
₆(OH)
₂·3H
₂O. It is a colorless to white mineral crystallizing in the monoclinic crystal system typically occurring as prismatic to acicular crystals or granular masses. It is relatively soft with Mohs hardness of 2.5 to 3 and light with a specific gravity of 1.91. It exhibits perfect cleavage and a brittle fracture.

Kernite is soluble in cold water and alters to tincalconite when it dehydrates. It undergoes a non-reversible alteration to metakernite (Na
₂B
₄O
₇·5H
₂O) when heated to above 100 °C.^[3]