Stonemasonry in the Říčany Region – Žernovka Quarry, Part 1

The last active quarry in the wider area of Mukařov is located on the north-western edge of Žernovka in a forest called Horka near the spot height 443. The access road to the quarry leads from Horka Street that goes from Žernovka to Babice.

It is a pit quarry with a bottom that is difficult to access, so the stone must be lifted by a crane or a cableway, and the blocks of stone can weigh no more than 5 tons. Established approximately 150 years ago, it has been kept by one family for several generations now. The stone is mined mostly for exterior use: paving stones, slabs, stair steps, columns, or curbs, but it can also be used to create works of art or gravestones.

Granite from Žernovka Quarry was used in the construction of the Štěchovice Dam or the Vinohrady railway tunnel, and in recent years also as cladding for the underground station Palmovka, or paving for the underground station Strašnická. After 2000 the granite from Žernovka was exported abroad, e.g. the Spanish Menorca.

Pit quarry in Žernovka in 2016.
Photo: B. Dudíková Schulmannová, 2016.

The local biotite granite with a small amount of muscovite is called the Říčany (Žernov) granite, and it is one of the youngest intrusions of the Central Bohemian Plutonic Complex (CBPC). The Complex is a large (~3200 km2) product of the late Devonian or early Carboniferous (circa 354 to 336 million years) igneous Andean arc masking the dividing line between the Moldanubian and the Teplá-Barrandian unit. Remnants of the metamorphic mantle, the so-called island zone, form regionally and contact metamorphic, mostly metabasic rocks from the Proterozoic to Devonian age. There are also more acidic, late proterozoic clay metavulcanites, as well as alkaline-calcareous orthogneiss found in Staré sedlo and Mirotice, which are a probably somewhat older (~370 million years) product of the magmatic activity of the same arc. The CBPC magmatic rocks were divided into several magmatic suites based on their age, petrological character and chemism. The so-called Říčany Suite is one of the youngest and most acidic ones.

For World of Stone provided by authors:
Barbora Dudíková Schulmannová, Vojtěch Janoušek, Tomáš Navrátil,
Václav Rybařík and Pavel Vlašímský