In the current YourSystemmaticCollection (YSC) auction closing tonight, as well as the usual range of rare minerals there is another mineral first seen here on e-Rocks.
George was talking with Roberto Bracco of YSC at Munich and told us to look out for the mineral bonacinaite; Roberto was involved in the analysis and publication.
Bonacinaite - Varenche Mine, Saint Barthelemy, Aosta Valley, Italy (TL)
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Bonacinaite is colourless but the manganese-rich environment here helps finding the minute crystals by giving them a very pale lilac hue. The rounded lilac globules here, up to 0.12 mm across, are made of tiny tabular crystals, as well as individual tabular crystals up to 0.06 mm across.
The association in picture includes pale blue thortveitite balls, bronze-colored wallkilldellite micro rosettes and brownish altered arseniopleite, thought to be the main source of arsenic
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In the item description Roberto tells us the mineral was originaly found back in 2005 but scarcity and the small crystal size made the characterization process really painstaking. His later personal find in 2016 yielded a handful of specimens that helped in the final analytical steps.
Bonacinaite is the first discovered natural and simple arsenate of scandium and is analogous to the scandium phosphate kolbeckite, both minerals are in the metavariscite group - MXO4 · 2H2O, where X = P or As - the formula for bonacinaite is, Sc(AsO4)·2H2O.
The species name is dedicated to Enrico Bonacina, mentor and beacon to Italian photograpers of the mineral micro world, turning 90 soon and still very active in sharing pictures and expertise.
