September 2024 – Hornblende

Hornblende belongs to the amphibole group and is the mineral of the month for September. Amphiboles are chain silicates, whereby the SiO₄ tetrahedra are linked together via corners. Amphiboles occur particularly in igneous and metamorphic rocks and are among the more common minerals. In the Alps, you may have already seen a hornblende schist. Apart from hornblende, this rock usually contains mica and garnets. This combination of minerals also tells us something about the formation conditions of these rocks in mountain belts. The study of hornblende is therefore important for many different scientific questions.

(Ca,Na,K)_2-3 (Mg,Fe,Al)₅ [(OH,F)₂ /(Si,Al)₂Si₆O₂₂

Locality: Bilin, Tschechien

Size: 4x11x8 cm (HxLxW)

Weight: 385 g