About this place
Malý Uran is a small but geologically remarkable nature reserve in the municipality of Jesenice, Rakovník District, Central Bohemia, straddling the cadastral territories of Oráčov and Kosobody. This nature monument covers 18.5 hectares and protects a steep slope and the edge of a spoil-heap plateau above the right bank of the Kosobodský stream, two kilometers north of the village of Sosen. The site lies within the Jesenicko Nature Park, which spans the western part of the district.
Where does the name come from?
The reserve's name — literally "Small Uranium" — refers directly to its industrial past: a uranium exploration adit, marked UP, dug here in the 1950s. The remains of the workings, known as Kosobody 1, sit roughly 70 meters from the edge of a sparse oak forest. The ground disturbed by the mining work measures about 60 by 30 meters. These rocky slopes, cut through by old excavations and heaps of mining spoil, give the site its distinctively raw, exposed character.
What lies in the rock?
Malý Uran holds real geological significance and is listed among the Czech Republic's important geological sites. It belongs to the Bohemian Massif, specifically the Barrandien unit, with rocks exposed here dating to the Proterozoic. Torbernite — a bright apple-green uranium mineral — has been identified in the weathered vein material, forming small platy crystals up to 1 millimeter across. The rock itself consists of heavily weathered slates or breccia, in places possibly locally silicified, coated with a yellow weathering crust that suggests the presence of jarosite. Transverse grooves running along the mineralized zones show slightly elevated radioactivity — a lingering trace of the mid-20th-century geological surveys that searched this ground for uranium ore.
Why was it protected?
The formal reason for the site's protection, declared in 1996, is its rocky slopes above the Kosobodský stream, covered with common juniper. The protected area includes thermophilic grasslands and juniper heathland, habitats that are now gradually reverting to forest through natural succession. This combination of an unusual mining history, rare uranium minerals, and valuable dry grassland habitat gives Malý Uran an outsized significance for such a small protected area.
How to get there
The reserve sits within the Jesenicko Nature Park, an area known for its network of hiking trails and the Jesenicko educational nature trail, which winds through the most interesting corners of this part of the Rakovník District. The nearest landmark is the village of Sosen, about two kilometers south of the reserve.
Frequently asked questions
What is Malý Uran? It is a small Czech nature monument protecting rocky slopes marked by a former uranium mine and valuable dry grassland vegetation.
Where does the reserve's name come from? It refers to a uranium exploration adit dug in the 1950s, whose traces are still visible in the landscape today.
What mineral can be found here? Weathered rock veins contain torbernite, a green uranium mineral that forms small platy crystals.
Since when has the area been protected? The site received legal protection in 1996, covering an area of 18.5 hectares.
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