• Chemistry: NH4B5O6(OH)4, Ammonium Borate Hydroxide.
  • Class: Carbonates
  • Subclass: Borates
  • Uses: Only as mineral specimens.
  • Specimens

Larderellite is a rare borate mineral. It is found at its type locality of Larderello, Val di Cecina, Piza, Toscana, Italy. Larderellite is formed from boron rich waters that steam out of volcanic exhalations. At larderello, the steam is used for the production of boric acid. The larderellite forms crusts that have a cotton ball-like quality and have a snow white color. In addition to the boron in its formula, larderellite has ammounium as well, making it a true chemical oddity in the mineral kingdom. Ammonioborite, (NH4)2B10O16 - 5H2O is another ammonium borate mineral which was also found at larderello.


  • Color is white.
  • Luster is vitreous to dull.
  • Transparency: Specimens are translucent.
  • Crystal System is monoclinic.
  • Crystal Habits include puffy, cotton-like crusts.
  • Cleavage is perfect.
  • Fracture is uneven.
  • Hardness is 1
  • Specific Gravity is approximately 1.9 (well below average)
  • Streak is white.
  • Associated Minerals include other rare boron minerals.
  • Notable Occurrence is limited to the type locality of Larderello, Val di Cecina, Piza, Toscana, Italy.
  • Best Field Indicators are habit, locality, luster, softness and density.
Popular Members of the Carbonates Class


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