.

Borax Mineral Facts:

Chemical Formula: Na₂B₄O₅(OH)₄ . 8H₂O
Hydrous sodium borate, 36.6% Boron trioxide by weight.

Colors: Borax has a white, grayish or bluish color and a white streak.

Hardness: 2.0 to 2.5
.
Density: 1.7

Cleavage: One perfect cleavage on  {100}.  Fracture is conchoidal and uneven: brittle.

Crystallography: Monoclinic

Luster:. Borax  is brittle, vitreous, resinous or earthy; is translucent to opaque. On exposure to the air the mineral loses water and tends to become white.

Optics: (Refractive Index)  =  a = 1.447; b = 1.469; y = 1.472
 

Composition, Structure and Associated Minerals:
The principal method of occurrence of the mineral is as a deposit from salt lakes in arid regions, and as incrustations on the surfaces of alkaline marshes overlying buried borax deposits. The original beds were deposited by the evaporation to dryness of ancient salt lakes, and the incrustations were produced by the solution of these deposits by ground water, and the rise of the solutions to the surface by capillarity.

Identification and Diagnostics
Borax is soluble in water, yielding a weakly alkaline solution. It is easily fusible (1-1.5) with much swelling and gives strong yellow flame (sodium) . Readily soluble in water. Turmeric paper, moistened with a dilute hydrochloric acid solution of the mineral, turns reddish brown when dried at 100 C. Borax yields much water when heated in the closed tube.

Industrial Uses of Borax
Borax is an important industrial commodity. The mineral borax was formerly obtained in the United States, especially in California, Oregon and Nevada, by the evaporation of the water of borax lakes, by washing the crystals from the mud on their bottoms and by the leaching of the mineral from marsh soil. At present, however, nearly all the borax of commerce is manufactured from colemanite.

Return to the Mineral Collectors Information Page

Nevada Outback Gems