The younger son of Johann Baptist Megerle (known as von Mühlfeld since 1803), Johann Georg Megerle von Mühlfeld, published the "Mineralogisches Taschenbuch", enthaltend eine Oryctographie von Unterösterreich zum Gebrauche reisender Mineralogen" (Mineralogical compendium containing an oryctography of Unterösterreich for the use of mineralogists on field trips); Mühlfeld had earlier been an honorary assistant in the entomological department of the Imperial Natural Cabinet. Although Stütz had completed this work, it had never been published. The booklet supplies us today with a host of information on sample collection in the greater area of Vienna. Schreibers succeeds also to raise the annual budget for the purchase of minerals significantly. The mineral collection thus acquires steady growth. The inventory of the earth science collection grew within a few years by several thousand specimens. In particular, a series of interesting meteorites - Campo del Cielo ("Tucuman"), Benares, Stannern (refer to "meteorite collection") Acting on Schreiber's proposal, it is arranged to devote a separate display room to these extraterrestrial bodies - the foundation for today's significant meteorite collection of the natural history museum is thus laid. The Abbot Rochus Schüch, already active in the reptile and fish department by 1814, is seconded on a temporary basis to the mineral cabinet, until his departure in 1817 and also holds lectures on mineralogy (FITZINGER, 1868).
Paul Maria Partsch, through his acquaintance with Schüch, becomes into contact with the Mineral Cabinet and assists not only in the work of classification but also with the arrangement and description of the Collection of the Oberstkämmerer and topmost chief of the Imperial Natural History collection, Rudolf Graf von Wrbna-Freudenthal.
In 1817 Schüch gives up his post as custodian to the cabinet to become librarian to archduchess Leopoldine, whom he had instructed in mineralogy. The hope of the Oberstkämmerer Count Wrbna as well as the director Schreibers, that Partsch, working intently on improving his mineralogical training, would secure the post of curator then becoming vacant, are not fulfilled, because of the intrigues of the all-powerful State Counsellor Freiherr von Stifft. Furthermore, Benjamin Scholz, curator there since 1811, resigned from the Mineralogical Cabinet, as he is appointed to the post of professor of chemistry at the "K.k. Polytechnischen Institut" (Imperial Royal Polytechnic Institute), now the Technical University of Vienna.
The marriage of the archduchess Leopoldine to Dom Pedro, Crown Prince of Brazil, induces Emperor Franz to equip a natural historical expedition to explore this giant country. The mineralogical aspects of the mighty enterprise are taken care of by Johannes Emanuel Pohl, acting professor in general natural history at Prague University, who has in State Counsellor von Stifft a benevolent patron. The expedition, in which more than ten persons take part at various times, among them the well-known painter Thomas Ender, lasts almost two decades and brings the Viennese collections rich booty in all areas. The items brought back to Europe are so extensive that a special museum, the so-called "Brazilian Museum" has to be installed in the Harrach House in the Johannesgasse (house No. 7 today). It was only after the closing of this museum in 1836 that the items are assigned to the corresponding collections. Minerals and rocks incorporated into the Naturalia Cabinet are itemised in a separate catalogue.
In 1821 the Mineral Collection is augmented considerably by the legacy of the "K.k. Staatskanzleirath" (Imperial Royal State Counsellor) van Hoppe, whose bequest includes a valuable collection of rings with emeralds, rubies, sapphires and diamonds, partly of the highest quality, as well as the collection of the court jeweller M. Cohen, who enriches it with a suite of raw and cut diamonds and the equipment for their processing.
In 1827, the famous mineral collection of the merchant Jacob Friedrich van der Null (later written as "van der Nüll") and revised and described by Friedrich Mohs is purchased for the Mineral Cabinet. This collection is variously described by contemporaries as the most beautiful and from a oryctognostic viewpoint the most important in Germany. In any case, van der Nüll purchased within approximately ten years no fewer than eleven important private collections, frequented mineral auctions, taking place in Vienna at this time and endeavoured to acquire the best samples from any find coming on the market. He carried out exchanges, tried to display the acquired specimens to their most advantageous and finally gave the mineralogist Friedrich Mohs the assignment to prepare the collection in an orderly manner and to set up a corresponding catalogue, taking the newest information in mineralogy into account (MOHS, 1804). Mohs uses this opportunity to present to his contemporaries his own concept of systematic mineralogy.
Following a proposal by the State Counsellor Freiherr von Stifft, Friedrich Mohs is charged with the task of reorganising the Mineral Collection in the Mineral Cabinet from 1827 onward, where he also holds his lectures until 1835, as he does not consider the corresponding University collection as appropriately suitable. Custodian Johann Carl Megerle von Mühlfeld and Paul Partsch, supervisor at the Mineral Cabinet, assist in the reorganisation of the collection; in addition, Maximilian, nephew to von Mühlfeld, assists voluntarily in this undertaking, which could actually be completed within the same year. The description of this revised collection is edited by PARTSCH (1828) . Apart from the chair at the University of Vienna, Mohs is also nominated to the vacant custodian's position in the Mineral Cabinet.
In September 1835, Mohs is released from his duties as custodian of the Mineral Cabinet and transfers to the Mining Academy (today's Mining University) in Leoben with a position of Bergrath (Mining Inspector). At the same time, Paul Partsch is appointed custodian of the Mineral Cabinet. At the end of 1835, custodian von Mühlfeld, who has custodial care of the collection since Stütz's time, also goes into retirement.
A collection of Russian minerals and rock-types is presented by Czar Nicholas I to Emperor Ferdinand I's "Vereinigte Naturalien-Cabinette" (United Imperial Royal Natural Resources Cabinetts). The most valuable object in this collection is a gold nugget from a secondary sedimentary deposit at Miask in the Urals, weighing 548 grams.
From the inventory of the Mineral Collection in 1844, a large portion of minerals and rocks is diverted and transferred to the newly founded "K.k Montanistisches Museum" (Imperial Royal Mining Museum), the predecessor to today's "Geologische Bundeanstalt" (Federal Geological Survey), Vienna (former the "K.k. Geologische Reichsanstalt / Imperial Royal Geological Institute); founded on 15 November 1849. It was only after the Second World War that parts of these are restored to the "Mineralogisch-Petrographische Abteilung des Naturhistorischen Museums" (Mineralogical-Petrographical Department of the Natural History Museum).
During the revolutionary year of 1848, the Natural Resources Cabinets suffer painful losses, as portions of the collections and the depots in the attic of the Hofburg are set on fire through artillery fire. In particular, the precious private library of Schreibers and many of his scientific notes are lost in the fire. The Mineral Cabinet itself is saved from destruction. Schreibers retires at the end of 1851; he dies on May 21 1852.