Mineral of the Month 2024

Die Hornblende gehört zu der Amphibolgruppe und ist das Mineral des Monats September. Amphibole sind Ketten-Silikate, wobei die SiO₄-Tetraedern über Ecken miteinander verknüpft sind. Amphibole treten ins besonders in magmatischen und metamorphen Gesteinen auf und gehören zu den häufigeren Mineralen. In den Alpen habt Ihr vielleicht auch schon einmal einen Hornblenden-Garbenschiefer gesehen. In diesem Gestein gibt es abgesehen von der Hornblende meistens noch Glimmer und Granate. Diese Kombination an Mineralen verrät uns auch etwas über die Bildungsbedingungen dieser Gesteine in Gebirgen. Somit ist die Untersuchung von Hornblenden von Bedeutung für viele unterschiedliche wissenschaftliche Fragestellungen.

Pycnite is the mineral of the month for August 2024. This beautiful mineral is a variety of topaz. A variety is the different formation of a mineral in terms of its colour, transparency, or habit Similar to pylknite, varieties often have their own minerals. The internal structure of the crystals in each variety is identical. This is also the difference to a modification, where the chemical composition is identical but the crystal structure is different. The best-known location where pycnite is found in Germany is Altenberg in Saxony.

Wait a minute, sphalerite was already a mineral of the month once, wasn’t it? That is correct. However, this year sphalerite was named Ore Mineral of the Year. This is the second time that the Ore Mineral of the Year category has been awarded by the International Mineralogical Association (IMA) Commission on Ore Mineralogy.

The mineral of the month was found by the young researcher Greta in the Isar river. However, to be precise, it is not a mineral but it is a rock. The grey colour also gives the name: It is greywacke. Under a magnifying glass, you can see many feldspars.

In May 2024, olivine holds the title of Mineral of the Month. However, olivine actually covers a mixed series of forsterite to fayalite. This means that there is a magnesium-rich end member (forsterite) and an iron-rich end member (fayalite). In such a solid solution, one element can be substituted by another element. With olivine, this is unconditional.

For the month of April 2024, we have chosen a rather rare mineral: Danburite. This mineral was named after the town of Danbury in Connecticut. Danburite belongs to the group of framework silicates and – which is not very common – incorporates the element boron.

Like most boron-containing minerals, danburite occurs in pegmatites. These rocks are formed from the residual melts that remain after the crystallization of granite. This residual melt contains an above-average amount of boron, which is then incorporated into minerals such as danburite.

In March 2024, magnesite holds the title of Mineral of the Month. Magnesite belongs to the group of carbonates and is predominantly formed hydrothermally. This means that magnesite precipitates from hot fluids. Due to the high temperature resistance of magnesite (up to around 3000°C), it is an important raw material for the production of refractory bricks, which are used to furnaces. China is the largest producer of magnesite with 20 million tons (2020). A special shape of magnesite is the so-called pinolite. A mixture of magnesite, dolomite and graphite. The white magnesite grains are reminiscent of pine nuts, hence the name pinolite. This is particularly well known from the Hohe Tauern in Austria.

This mineral with its beautiful pink color is the mineral of the month for February. Rhodochrosite is also known in German as “raspberry spar” or “manganese spar”.

The mineral of the month for January 2024 is rutile. This mineral is often found in metamorphic rocks, igneous rocks and heavy mineral sands. Rutile crystallizes in the tetragonal crystal system and usually develops short to long prismatic crystals.