Kunčický bludný balvan, Natural monument in Kunčice, Czech Republic

Kunčický bludný balvan is the largest known erratic boulder in the Czech Republic, an ellipsoid block of coarse-grained porphyritic granite measuring 320 × 250 × 155 cm and weighing 17.5 tonnes. Its yellowish grey-pink rock holds 1–2 cm phenocrysts of pink and yellowish potassium feldspar, along with plagioclase, crushed quartz, biotite, magnetite, apatite and rare epidote. It rests on a concrete base on Vratimovská street in Kunčice.

The boulder was found in 1954 during foundation work for the Nová huť Klementa Gottwalda foundry and was lifted from a depth of 6.8 m. It was declared a natural monument on 1 January 1990, not at the time of the find.

The boulder represents a tangible connection to the Ice Age, showing how glaciers moved massive rocks across the landscape. Today, the site offers a direct way to understand the geological forces that shaped this region.

The boulder is located near the southern entrance of a former foundry complex that is accessible by public transport. The site has a relatively flat layout that makes reaching the stone straightforward.

This is one of the largest known erratic boulders in the Czech Republic and owes its preservation to a chance discovery during construction work. The exact source of the granite and the distance it traveled during the Ice Age remain partly mysterious.