One white crystal group of the very rare arsenate-borate mineral teruggite from the TL in Loma Blanca, Argentina and only one of three known localities worldwide. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Teruggite
A colorless hydrated calcium-magnesium arsenate-borate.
Intro adapted from Wikipedia (CC BY-SA).
Teruggite is an IMA-recognized mineral species in the borate class, with the chemical formula Ca₄Mg[AsB₆O₁₁(OH)₆]₂·14H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a).
Key properties: Mohs hardness 2.5; specific gravity 2.15–2.2; Vitreous luster; optically biaxial.
IMA symbol Tgg, IMA status: approved, named in 1968.
Found in lacustrine borate deposits, typically in association with volcanic hot springs and diagensis of playa sediments.
It is found associated with Inyoite, calcite, ulexite, aragonite, realgar, montmorillonite (Loma Blanca deposit, Argentina); colemanite, meyerhofferite, ulexite (Emet deposits, Turkey).
The mineral was named to honor Mario E. Teruggi, Professor of Sedimentology and Petrology, National University, Plata, Argentina.