Husova kazatelna, Natural monument in Petrovice, Czech Republic.

Husova kazatelna is the largest rocking stone in the Czech Republic: a durbachite boulder 4 m long, 2.5 m wide and 2.7 m high, its dark colour coming from amphibole and biotite, with white feldspar crystals up to 2 cm across. Around it lie boulder herds and several-metre rock blocks of the same rock, including the split Čertův kámen.

The boulder is a durbachite block of Čertovo břemeno, a deep-seated magmatic rock whose dark colour comes from amphibole and biotite, with white feldspar crystals up to 2 cm. It was shaped over millions of years by weathering and erosion-denudation. The 9.07 ha natural monument was declared in 1977.

The name Husova kazatelna comes from a legend that Jan Hus preached from this stone on his way to Kozí Hrádek. Other local tales call it Čertova kazatelna, and nearby boulders carry names like Zkamenělá žába, Hřib and Pecen chleba.

The site sits at roughly 513 meters elevation and connects easily to marked walking trails in the area. Wear sturdy shoes and follow the colored route markers to reach the boulder safely from nearby paths.

A natural basin sits atop the boulder, carved by selective erosion and the dissolving action of water on the rock's mineral composition. This hollow reveals how different parts of the stone weather at varying rates.