page_title: Borax
section_title: Small-scale gold mining
hierarchical_section_title: Borax / Uses / Small-scale gold mining
caption_attribution_description: Traction steam engine hauling borax, Death Valley, California.
context_page_description: Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is a compound with formula Na
  ₂H
  ₄B
  ₄O
  ₉•nH
  ₂O or, more precisely, [Na•⁺
  ₘ]
  ₂ [B
  ₄O
  ₅(OH)²⁻
  ₄].
  The formula is often improperly written as Na
  ₂B
  ₄O
  ₇•H
  ₂O, reflecting an older incorrect understanding of the anion's molecular structure. The name may refer to any of a number of closely related boron-containing mineral or chemical compounds that differ in their water of crystallization content. The most commonly encountered one is the octahydrate Na
  ₂H
  ₄B
  ₄O
  ₉•8H
  ₂O or [Na⁺
  ₄]
  ₂ [B
  ₄O
  ₅(OH)²⁻
  ₂]. It is a colorless crystalline solid that dissolves in water.
  Borax is a component of many detergents, cosmetics, and enamel glazes. It is used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound, in the manufacture of fiberglass, as a flux in metallurgy, neutron-capture shields for radioactive sources, a texturing agent in cooking, as a cross-linking agent in slime, as an alkali in photographic developers, as a precursor for other boron compounds, and is useful as an insecticide.
context_section_description: Borax is replacing mercury as the preferred method for extracting gold in small-scale mining facilities. The method is called the borax method and is used in the Philippines.
caption: Traction engine hauling borax, Death Valley, 1904
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