Kernite

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Hydrated sodium borate hydroxide mineral

title: "Kernite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["sodium-minerals", "inoborates", "monoclinic-minerals", "minerals-in-space-group-14", "natural-history-of-kern-county,-california", "natural-history-of-the-mojave-desert"] description: "Hydrated sodium borate hydroxide mineral" topic_path: "history" source: "https://en.wikipedia.org/wiki/Kernite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Hydrated sodium borate hydroxide mineral ::

::data[format=table title="Infobox mineral"]

Field	Value
name	Kernite
category	Inoborates
image	Kernite - USGS Mineral Specimens 692.jpg
formula
IMAsymbol	Ker
molweight	273.22 g/mol
strunz	6.DB.05
system	Monoclinic
class	Prismatic (2/m)
(same H-M symbol)
symmetry	P21/c
unit cell	a = 7.0172(2)
b = 9.1582(2)
c = 15.6774(5) [Å]
β = 108.861(2)°; Z = 4
color	Colorless, white
habit	Crystalline - occurs as well-formed coarse sized crystals
cleavage	Perfect on [100] and [001], good on [201]
fracture	Splintery
tenacity	Brittle
mohs	2.5-3
luster	Vitreous - pearly
refractive	nα=1.454, nβ=1.472, nγ=1.488
opticalprop	Biaxial (-)
2V	80°
birefringence	δ =0.0340
streak	White
gravity	1.9 - 1.92
other	Non-radioactive, non-fluorescent, non-magnetic
references
::

Kernite, also known as rasorite, is a hydrated sodium borate hydroxide mineral with formula . 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 () when heated to above 100 °C.

Occurrence and history

The mineral occurs in sedimentary evaporite deposits in arid regions.

Kernite was discovered in 1926 in eastern Kern County, in Southern California, and later renamed after the county. The location was the US Borax Mine at Boron in the western Mojave Desert. This type material is stored at Harvard University, Cambridge, Massachusetts, and the National Museum of Natural History, Washington, D.C.

The Kern County mine was the only known source of the mineral for a period of time. More recently, kernite is mined in Argentina and Turkey.

The largest documented, single crystal of kernite measured 2.44 x 0.9 x 0.9 m3 and weighed ~3.8 tons.

Uses

Kernite is used to produce borax which can be used in a variety of soaps.

References

Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
[http://webmineral.com/data/Kernite.shtml Kernite WebMineral]
[http://rruff.geo.arizona.edu/doclib/hom/kernite.pdf Handbook of Mineralogy]
[http://www.mindat.org/min-2188.html Kernite on Mindat.org]
P. C. Rickwood. (1981). "The largest crystals". American Mineralogist.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::