Ochtinská Aragonite Cave

Inside a low hill in southern Slovakia, white needles and branching clusters of aragonite spread across the ceilings and walls like frost, so dense in places that they recall a starry sky. Ochtinská Aragonite Cave is only about 300 metres long, but it is one of very few caves in the world whose decoration is made almost entirely of aragonite rather than ordinary calcite dripstone, and it was opened to the public in 1972 as one of only a handful of accessible aragonite caves anywhere.

No natural entrance ever existed. The cave was found by chance in 1954, when Martin Cangár and Jiří Prošek, workers of a mineral prospecting company, broke into it while driving an exploratory gallery. It lies in a lens of ancient Devonian limestone and ankerite surrounded by non-karst phyllite rock, and its narrow, upward-tapering passages and chambers were dissolved by slowly moving water mixing along tectonic fractures. A man-made tunnel about 145 metres long, dug from 1966, now leads visitors in to the cave level at 642 metres above sea level.

The air inside holds steady at 7.2–7.8 °C with very high humidity, and the dripping water is rich in magnesium, iron and manganese — the conditions that let aragonite crystallise instead of calcite. Three generations of it have been identified. The oldest, milky kidney-shaped crusts, have been dated to roughly 120,000–138,000 years; the most abundant, around 14,000 years old, forms needles several decimetres long and curling, spiral helictites grouped into bushes, including the forms known as "iron flower"; and the youngest appears as tiny fans just a few millimetres across on the iron-rich ochre sediments. The best-known chamber is the Milky Way Hall, where the white branches glitter against the darker ceiling. Since 1995 the cave has been part of the UNESCO World Heritage Site Caves of Aggtelek Karst and Slovak Karst, shared with Hungary, and it is protected as a national natural monument.

The cave sits on the north-western slope of Hrádok hill in the Revúca Highlands, between the small towns of Štítnik and Jelšava, west of the town of Rožňava.

Getting there

The cave is about 17 km from Rožňava in a straight line; by road it is roughly 25 km via Štítnik towards Jelšava, with a turn-off from the road on Hrádok hill. The nearest bus stop is Gočaltovo, Hrádok. The nearest airport is Poprad-Tatry (TAT), about 46 km away in a straight line and around 80 km by road via Dobšiná and Štítnik.