Mineral Information and Data:

Borax
Na2B4O5(OH)4 • 8H2O [CNMNC approved formula]

Named from the Arabic buraq, for "white".

IMA status : Valid species (Pre-IMA 1753) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
26.04.01.01  
  (26) Hydrated Borates Containing Hydroxyl or Halogen
  (26.04)
  (26.04.01)
  
Nickel-Strunz
(10th edition) :
06.DA.10
  (06) Borates
  (06.D) Tetraborates
  (06.DA) Neso-tetraborates
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Space group: B2/b
Unit cell: a = 12.2012(2) Å, b = 10.644Å, c = 11.879Å, β = 106.617(1)°
Crystal Habit: Crystals are commonly short to long prismatic [001] and somewhat flattened on {100}, showing {100}, {110}, {001}, {112}, {111}, {010}, {021}, to 10 cm, typically distorted; commonly massive.
Twinning: Rare on {100}
  
Color: Colorless to white, pale gray, pale blue, pale green; colorless in transmitted light
Diaphaneity: Translucent to opaque
Luster: Vitreous to resinous, may be earthy
Hardness (Mohs): 2 - 2.5
Measured Density: 1.715(5) g/cm3
Cleavage: {100}, perfect; {110}, less perfect; {010}, in traces
Tenacity: Brittle
Fracture: Conchoidal
Streak: White
  
Geologic Setting: In evaporite deposits, salt lakes, playas, commonly well-crystallized; as an efflorescence on soils in arid regions.
Mineral Association: Inyoite, ulexite, colemanite, kernite, kurnakovite, trona, aphthitalite, glauberite, calcite, nitratine, gaylussite, hanksite, halite, gypsum
Ore deposits: A chief source of boron.
  
Other Properties: Diamagnetic (repelled from magnetic fields). H2O Soluble.

 

Borax
Origin: U.S. Borax Open Pit, Boron, Kern Co., California
Sample size: about 2 cm
Photo and Owner: Milton Speckels

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