Emperor Leopold II (1747-1792) followed Joseph II after the latter's death in 1790 as sovereign. Although he was only two
years in office, he also enlarged the extent of the collection by his purchase of the opulent mineral collection of Field
Marshall Andreas Count of Hadik. Leopold II was succeeded on the Imperial Throne by Franz II (1768-1835). Due to the events
of the Napoleonic Wars, Franz II renounced the Imperial crown of the Holy Roman Empire in 1806, remaining Emperor of Austria
as Franz I.
However, long before then, i.e. in 1788, Andreas Xaverius Stütz, Professor of Natural History and Geography and formerly canon
of the choirmasters of St. Augustine, becomes Assistant Director of the Natural History Collection, replacing Karl Haidinger,
who is appointed Mine and Professor of Mathematics and Mechanics at the Mining Academy in Schemnitz.
Stütz had been long concerned with the geognostic conditions at his native Lower Austria and had published several mineralogical
papers. He begins, supported by the custodian Johann Carl Megerle, who particularly took care of the minerals and part of
the Mollusc Collection, with the subject which all co-workers had avoided until then, the inventory-taking of specimens from
the geosphere. Using these data, a catalogue of specimens of natural historical interest, the "Catalogus Stützianus" was drawn
up; it was hand-written, possibly by Stütz himself. Although an entry-book ("Einschreibebuch") had existed since 1780, it
was clearly not used in every case and the inventory numbers, issued at a much later date, but still valid to date, are not
entered. The same applies to a series of loose-leaf archive-pages and notes by mineralogists from earlier times. The co-ordination
of the old pre-1797 mineral samples in the collection is very difficult, if possible at all. As pointed out previously, the
"Catalogus Stützianus" augured a new era for the Viennese Mineral Collection.