Mineral of the Month 2023

Due to many requests, rose quartz has finally been chosen as the mineral of the month. Yay!!! Rose quartz is a variety of the mineral quartz. A variety is a different formation of a mineral in terms of its color, transparency, or habit. Color variations can be caused by a slight change in the chemical composition (trace elements) or by radioactive radiation, for example. The coloration of rose quartz has not yet been fully clarified and there are different opinions. However, the most common publications and studies show that microscopically small fibrous inclusions of a pink borosilicate, related to dumortierite, are responsible for the coloration in rose quartz. Rose quartz is found in granitic pegmatites and hydrothermal veins. In our museum there is also a large rose quartz you can touch – come and see it again!

The mineral of the month for November is certainly also known to many as a gemstone. Labradorite is characterized in particular by its beautiful play of colors. A mixture of interference and reflection of light on tiny sub-microscopic segregation lamellae creates this special feature of labradorite. From a mineralogical point of view, labradorite is a plagioclase and therefore also belongs to the feldspar group. It is named after the Labrador Peninsula in Canada. Labradorite was probably first discovered there at the end of the 18th century.

Johann Wolfgang von Goethe was also intensively engaged in scientific questions. His main interest was geology and mineralogy. Therefore, it is perhaps not surprising that there is a mineral named after him – our mineral of the month October. Goethite is a common mineral from the mineral class of “oxides and hydroxides” of black-brown to black or light yellow color due to weathering. However, the so-called streak color differs from this, because goethite has a yellow-brown streak color. The streak color refers to the color of the mineral powder, which is used as a simple identification method to distinguish between minerals that appear similar on the outside. To determine the streak color, the mineral is rubbed with some pressure over a mostly white hard porcelain tablet. Goethite, as in this case here, often develops needle and radial crystals.

The mineral of the month September is the pyrrhotite. Pyrrhotite often occurs in magmatic ore deposits. In these deposits, it is usually closely intergrown with chalcopyrite and pentlandite. In magmatic deposits, such as the Bushveld Complex in South Africa, it is also of economic interest because it also incorporates nickel into its structure. The exhibit for the mineral of the month comes from Trepča. A very well known locality for minerals (especially sphalerite).

In the context of our current special exhibition “Blühende Minerale” a sand rose may not be missing in the category mineral of the month. Therefore, the mineral of the month August is this beautiful small sand rose. Of course, this is not a petrified rose. It is only the rose form, which gives the name. Mineralogically it concerns in this case gypsum. These sand roses are formed in hot and dry desert areas. The special climatic conditions ensure that groundwater is brought to the surface by capillary forces. The content for the mineral gypsum are dissolved in this water. Due to evaporation and supersaturation of the solution, gypsum crystallizes in these characteristic leaf-shaped structures. The most famous sand roses are found in North Africa. In our exhibition you can see and even touch several large sand roses. So feel free to come by again sometime!

These beautiful green crystals, are the mineral of the month July. Pyromorphite crystallizes in the hexagonal crystal system. This can be seen also very nicely at the crystals. Typically pyromorphite occurs near the surface in connection with lead deposits. Thereby pyromorphite is formed secondarily as a weathering product of minerals like for example galena. And somehow this mineral also reminds of a nice collection of green plants or a green meadow, doesn’t it? Of course, this also fits to the special exhibition FlowerPower, which you can see until October.

The mineral of the month is barite, which is also known under the German name “Schwerspat”. The synonym also already reveals its special feature: high density. This property also conditions the application of barite, since most of the world’s production is used for drilling mud in deep wells. These are particularly necessary for oil and gas wells as well as geothermal energy. Well-known deposits in Germany include the Clara mine. Barite is also still mined there and finds special applications. The largest producers worldwide are China, India and Morocco. Vereinigung der Freunde der Mineralogie und Geologie e.V has chosen barite as the mineral of the year 2023.

This month the category Mineral of the Month is fitting for the new special exhibition “Flowering Minerals”. In this special exhibition we see the connection between botany and mineralogy. Some minerals look like flowers, such as the sand rose and this wood opal. But also the topic of symmetry is explained in the exhibition and why there are differences between flowers and minerals in symmetry. Other topics include display plants, fertilizers, biomining, rocks and wine, and fossils.

The German term “Zinkblende” reveals what the mineral sphalerite is chemically – a zinc sulfide. Sphalerite crystallizes in the cubic crystal system and develops mostly tetrahedral and dodecahedral crystals. Depending on the exact composition, sphalerite has a yellow, red, brown or black color. Sphalerite is of economic interest because it can also incorporate gallium, germanium and indium. These are important elements for industry and technology.