Streaming from a volcanic rock at the foot of the Ciomad Massif – the youngest volcano in the Harghita Mountains, the Izvorul Zanelor spring water passes through the andesite blocks and it infiltrates through the volcanic ashes and sands. These processes ensure natural filtration and purification. The area from which Izvorul Zanelor originates from is a protected hydrological periphery.
The Ciomad-Puturosu Massif is a young volcanic formation of the Harghita Mountains, being made up by the Bolondos Mountain, the Puturosu Mountain and the Balvanyos Peak. The Massif was formed due to a crustal fracture that took place in between the fraction - line of the Oriental Carpathians and the Transylvanian Depression. The main part of the volcanic formations date back to the Pliocene era, precisely to the third volcanic cycle.
In the Depression area the sedimentary formations prevail (sand, clay, marl, stones) being randomly scattered on a crystalline foundation. As a result of the post-volcanic manifestations the ample carbon dioxide emissions get into contact with the infiltrating water streams which they encounter, and due to this they surface as carbonated, bicarbonated, calcic and salty mineral waters.
Beside these mineral waters the carbon dioxide, hydrogenic and sulphurous emissions are also extremely valuable. The Tusnad springs are situated along the Olt river valley and have a great yield, giving birth this way to different peat bogs which are in the same time botanical reservations as well.