Hall IV ("Gemstone Hall")

Systematic Mineralogy, precious stones and ores. The paintings in this Hall mostly depict geological phenomena. Alongside and between the paintings there are caryatids, allegorical figures, whose emblems represent the most important metals and minerals. In this connection, it is interesting to note that the artist, Rudolf Weyer, based his depictions of several of the minerals on the actual specimens contained in the mineral collection (e.g., cassiterite/Schlaggenwald; gypsum/Eisleben, and galenite/Neudorf).

Four glass cabinets in this Hall are devoted to the systematic mineral show (phosphates and silicates). Among these objects, the following are of particular note: liroconite/Wheal (IV/2); phenacite/Habachtal ((IV/5); axinite/Bourg d'Oisans (IV/5); epidote/Knappenwand (IV/15); astrophyllite/Mont St.-Hilaire (IV/23); serandite/Gross Meseritsch (IV/32); kainosite (cenosite)/Obersulzbachtal (IV/33); hiddenite/Alexander County (IV/38); beryl/Acworth (IV/40); euclase/Rauris (IV/57); phlogopite/Wakefield (IV/60); datolite/Habachtal (IV/72).

Along one short end of the Hall (towards the Maria Therersien Platz), there are glass cabinets situated to the left and right of the windows, in which one can view the fluorescence of certain minerals under ultraviolet light. In the cabinet in front of the windows there is a display of synthetic gemstones.

In the corner of the Hall, there are several plates of flexible sandstone (Itakolumite), one of which dates back to the 18th century.

The rock collection is located in the cabinets along the side walls. Commencing at the large board (in IV/186-188) which depicts the cycle of creation of rock formations, one can see samples of the various rocks from diverse locations, put together in a systematic form: plutonites, volcanites, metamorphites and sediments.

The collection of gems and precious stones can also be found in this Hall. This collection is one of the most comprehensive and valuable of its kind to be found on the European continent. One cabinet contains significant specimens of most of the well-known jewellery material today, whereby the raw material and the half-finished stones are placed alongside the finished cut and polished stones together with pieces of original jewellery. Two side cabinets contain larger samples of the precious stones collection.

The following samples of the precious stones collection are worth mentioning: Native silver, Kongsberg (IV/101); taaffeite, Sri Lanka (IV/102); azurite/Tsumeb (IV/107); brasilianite/Galilea Mine (IV/107); almandine box/Lölling (IV/110); emerald (trapiche)/Muzo (IV/113); euclase/Miami (IV/124); brasilianite/Espiritu Santo (IV/123); kunzite/Urupuca (IV/123); rhodochrosite/Alma (IV/124); native silver,/Kongsberg (IV/144), and "Peru" (IV/146).

The most valuable and historically significant pieces of the collection are stored in safety cabinets. Particular pieces of note include: An opal from Czerwenitza exhibiting a fabulous array of colours, which is the largest of its kind, weighing 594 grams; diamonds in matrix from various South African deposits; a perfect, pale yellow octahedra also from South Africa, weighing 82.2 carats ,as well as cut and polished diamonds from India, partly coloured, of the highest quality; a platinum nugget from the Urals weighing 6.2 kg; Colombian emeralds, of partly excellent quality; the famous Bouquet of precious stones; a cut, flawless alexandrite from the Urals, weighing 12.8 carats with the finest colour change from red to green; one of the largest tourmaline groupings from the King Tourmaline Mine in California; top-quality rubies and sapphires set in rings, and an aquamarine crystal from Nepal weighing 1.6 kg.

A large amethyst sample with deep violet coloured crystals from the Serra do Mar in Brazil was a gift from Isidor Weinberger in 1904. In 1978, a topaz crystal weighing 117 kg was incorporated into the collection. It is one of the largest topazes from the deposit at Fazenda do Funil near Santa Maria do Itabira in Minas Gerais, Brazil, a pegmatite which is famous for the huge size of its crystals.