Ameghinite, formula- Na[H4B3O7] or NaB3O3(OH)4, is a mineral found in Argentina. It is a soft mineral with a Mohs hardness of 2-3. Ameghinite has a monoclinic crystal system. It is a soft monoclinic mineral, basically found in Argentina.

It was first described in 1967 as an occurrence in the Tincalayu Mine, Salar Del Hombre Muerto, Salta, Argentina. It was named for Argentine geologist brothers, Carlos Ameghino (1865–1936) and Florentino Ameghino (1854–1911).

General Information:

  • Category: Nesoborates
  • Formula: Na[H4B3O7] or NaB3O3(OH)4
  • Crystal system: Monoclinic
  • Crystal class: Prismatic (2/m)
  • Color: Colorless
  • Lustre: Vitreous
  • Hardness: 2 – 3

Physical Properties of Ameghinite

  • Transparency: Transparent
  • Hardness: 2 – 3 on Mohs scale
  • Tenacity: Brittle
  • Cleavage: Very Good {100}, very good; {001} and {010}, poor.
  • Fracture: Conchoidal
  • Luminescence: Fluorescent and phosphorescent, Short UV=strong pale blue, Long UV=strong pale blue.
  • Streak: white

Occurrence: Formed in massive borax in a borate-rich playa.

Association: Tincalconite, borax, ezcurrite, rivadavite.

Distribution: From the Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province,


Type Material: Natural History Museum, Paris, France; Harvard University, Cambridge, Massachusetts, 109054; National Museum of Natural History, Washington, D.C., USA, 137297.


Information Source;