Eclogite

Eclogites are massive rocks of greenish colour, which comes from the mineral omphacite - part of the pyroxene family. Other common minerals are garnets – like almandine or pyrop, occasionally accompanied by disthene (cyanite) or rutile. Eclogites are close to basalts in chemical composition as they are formed by high-pressure metamorphosis of basalts.  Krušné hory eclogites represented by the spectacular cliff on the Meluzína peak, were formed under extreme conditions during Hercynian (Variscan) continental collision. The estimated metamorphic conditions yield depths of 120 km with temperatures of 600 to 950°C and pressure 3 to 4 GPa.

Among the rocks on the Earth surface, eclogites are characterized by the highest specific weight. One cubic meter block weights about 3.5 tons. For comparison – basaltic block of the same size would be around 3 tons and granite 2.75 tons. Eclogites are also very hard and resistant and were used in the production of stone axes.

Besides Krušné hory Mts., smaller eclogite outcrops can be found in Slavkovský les and Tepelá Highlands.

Sample donated Lesy České republiky, s.e. – Regional directorate Western Bohemia.