Doupňák was declared a natural monument in 1993 and it covers a total area of 12 hectares. The reserve is found in the district of Chomutov in the region of Ústí nad Labem in the foothills of the Krušné Mountains, not far from the town of Klášterec nad Ohří towards the top of Holubí Peak and adjacent slopes.

The protection extents to the historically important mineral deposits of amethyst and jasper, that are identical to those used to decorate Prague Castle and Karlštejn in the Middle Ages.
The actual national natural monument, situated in the foothills of the Krušné Mountains, is covered with mixed, non-indigenous forests featuring mostly European Spruce, Scots' Pine, European Larch, Silver Birch and oak. The vegetation of the local non-indigenous forests is fairly poor, although you can find an abundance of Wavy Hair-Grass, various species of Hawkweed, cranberries and also for example Thumbell White. There are no especially protected species here.
Also the fauna to be found in this protected area is not so distinctive. Apart from the common species living in the woods, you can find here the protected Barred Warbler and slow-worm. Also the Northern Goshawk was recorded here, and the Eurasian red squirrel.

However, in terms of mineralogy this area is one of the most important protected areas in the northwest of Bohemia. Doupňák National Natural Monument, similarly to the nearby Ciboušov National Natural Monument are in terms of mineralogy and archeology locations of European importance. This locality is unique, in particular, thanks to the rich deposits of precious stones such as the different types of quartz.