Kernite

Kernite with Tincalconite Locality  : Kramer District, Boron, Kern County, California (Type Locality for Kernite) Dimensions : 14 x 3 x 2 cm. © johnbetts-fineminerals

Chemical Formula: Na
2
B
4
O
6
(OH)
2
·3(H
2
O)

Locality: Boron, Kern County, California, the county that contains the fabulous borate deposits at Kramer.
Name Origin: Named after it’s locality.

Kernite, also known as rasorite is a hydrated sodium borate hydroxide mineral with formula Na
2
B
4
O
6
(OH)
2
·3(H
2
O)
, 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
2
B
4
O
7
·5(H
2
O)
) 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.

Physical Properties

Cleavage: {100} Perfect, {001} Perfect, {201} Good
Color: Colorless, White.
Density: 1.9 – 1.92, Average = 1.91
Diaphaneity: Transparent to translucent
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 2.5-3 – Finger Nail-Calcite
Luminescence: Non-fluorescent.
Luster: Vitreous – Pearly
Streak: white

Photos :

Kernite Locality: Boron, Kramer District, Kern County, California (Type Locality for Kernite) Overall Size:    10x9x5 cm Crystals: 9 cm © JohnBetts-FineMinerals
Kernite Locality: Kramer District, Kern County, California (Type Locality for Kernite) Overall Size:    4.5c3c3 cm Crystals: 45 mm © johnBetts-FineMinerals
U.S. Borax open pit (Boron pit), U.S. Borax Mine (Pacific West Coast Borax; Pacific Coast Borax Co.; Boron Mine; U.S. Borax and Chemical Corp.; Kramer Mine; Baker Mine), Kramer Borate deposit, Boron, Kramer District, Kern Co., California, USA
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