Ammonioborite
Ammonioborite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (NH₄)₃B₁₅O₂₀(OH)₈·4H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: specific gravity 1.765; optically biaxial.
IMA symbol Abo, grandfathered status — known before the IMA’s founding, named in 1933.
Found in boric acid-rich fumarolic lagoons.
It is found associated with Sassolite, larderellite.
The name refers to its composition, ammonium borate.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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