Fontarnauit: New mineral discovered

Researchers describe previously unknown borate sulfate salt from Turkey

Fontarnauite crystals in the rock © Universidad de Barcelona
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Geologists have discovered a new mineral in western Turkey. The previously unknown double salt of borate and sulfate with sodium and strontium forms small, brownish crystals with a pearl-like luster. The mineral has now been officially recognized by the International Mineralogical Association and was named Fontarnauit.

The new mineral was discovered in the borate formations in western Anatolia. Here, about ten million years ago, during the Miocene, there was a vast area of ​​active hydrothermal springs and vast shallow pools. Due to evaporation, borates were deposited here, boron-containing salts, which are nowadays mined as raw materials for chemicals.

Unknown crystals in borate deposit

In one of these deposits, Federico Ortí and his team from the University of Barcelona encountered unusual brownish crystals during a drilling in 2009. These semitransparent and pearlescent crystals were once thought to be formed in rock spores and small canals that accumulated the concentrated leaches of high potassium and strontium hydrothermal waters.

As chemical analyzes have shown, the fontarnauite crystals correspond to a previously unknown, eighth variant of a borate-sulfate mineral. Boron and sulfur bind with sodium and strontium, with smaller amounts of potassium and calcium, the researchers report. The preliminary formula of these complexes is Na2SrSO4 [B4O6 (OH) 2] • 3H2O.

The name of the new mineral honors materials researcher Ramon Fontarnau i Griera, who headed the material characterization department at the University of Barcelona and made important contributions to mineralogy. display

(Universidad de Barcelona, ​​04.02.2015 - NPO)