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All About Death Valley Borax

Cottonball
Borax "cotton ball", made up of the hydrous borate minerals ulexite and proberite. Photo from NPS archives.
Borax basics
Uses for borax
Death Valley borate minerals

Borax basics

Pure boron is never found in nature because of its strong attraction to oxygen. However, over 100 minerals, called borates, contain boron and oxygen (borate radical, BO) as important constituents.

There are two basic types of borate minerals. The relatively rare anhydrous borates, which have no water incorporated into their structure, are found in metamorphic and igneous rock. Hydrous borates, minerals with water incorporated into their structure, form by the evaporation of mineral-rich water (evaporite minerals) on desert playas.

Reagan with Boraxo
Borax is an ingredient in many laundry products. Photo from NPS archives.

Hydrous borates are relatively soft, white, colorless, or transparent minerals. Ulexite, colemanite, and borax are the most common borate minerals found in Death Valley.

Uses for borax

Boron compounds have many household and industrial uses. Boron is a common ingredient of soaps, cleansers, herbicides, soldering fluxes, gasoline antiknock compounds, pharmaceuticals, water softeners, food preservatives, and fire retardants. Boron is also added in the manufacture of glass, pyrex, and porcelain enamels used on kitchen appliances, sinks, bathtubs, stoves, and other products.

Borate Minerals in Death Valley

After H. Majmundar,1985

Mineral name

Composition

Sodium borates:
Borax Na2B4O7 10H2O
Sborgite Na2B5O8 5H2O
Tincalconite Na2B4O7 5H2O
Calcium borates:
Colemanite Ca2B6O11 5H2O
Ginorite Ca2B14O23 8H2O
Gowerite Ca2B6O10 5H2O
Inyoite Ca2B6O11 13H2O
Meyerhofferite Ca2B6O11 7H2O
Nobleite CaB6O11 4H2O
Priceite Ca4B10O19 7H2O
Magnesium Borates:
Hungchaoite MgB4O7 9H2O
Inderite Mg2B6O11 15H2O
Kurnakovite Mg2B6O11 15H2O
Macollisterite Mg2B12O20 15H2O
Strontium borate:
Tunellite SrB6O10 4H2O
Sodium-calcium borates:
proberite NaCaB5O9 5H2O
Ulexite NaCaB5O9 8H2O
Sodium-magnesium borate:
Rivadavite Na6MgB24O40 22H2O
Sodium-silicon borate:
Searlesite NaBSi2O6 H2O
Calcium-magnesium borates:
Carboborite Ca2Mg(CO3)(B2O5) 1OH2O
Hydroborocite CaMgB6O11 6H2O
Wardsmithite Ca5MgB24O42 30H2O
Calcium-silicon borates:
Bakerite Ca8B10Si6O35 6H2O
Howlite Ca2SiB5O9(OH)5
Calcium-strontium borate:
Valkovite (Ca,Sr)2B14O23 8H2O
Natural boric acid:
Sassolite H3BO3
Harmony borax in time
geologic time scale
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