Praid Salt Mine

Praid Salt Mine Overview

Praid Salt Mine is a rock salt mine in Romania, located in Harghita County. The mine is situated in the Gurghiu Mountains basin, encompassed within the Salt Hill, forming the triangle Praid - Ocna de Jos - Ocna de Sus.

Geological Formation

The salt deposits in Transylvania (systematically exploited over time at Ocna Dejului, Sic, Cojocna, Turda, Ocna Mureș, Ocna Sibiului, and Praid) were formed 13.5 million years ago, in a shallow sea under a very warm tropical climate. The respective geological layer corresponds to the middle Miocene.

• The salt layer extends throughout the subsurface of Transylvania, with an average (original) thickness of about 400 m.
• The thick layers of sediments deposited later above the salt horizon have exerted immense pressure on the malleable and plastic salt layer, which sought weaker areas of the Earth's crust at the edge of Transylvania.
• This resulted in the formation of mushroom-like structures over 1,000 m high, often reaching the Earth's surface (as seen in the locations with ancient salt exploitation mentioned above).

The salt body at Praid has a slightly elliptical shape in horizontal plan, with diameters of 1.2 and 1.4 km, and based on exploration boreholes (S ACEX 401/1949 and S 110/1973), it is estimated to have a depth of 2.6 - 2.8 km, making it the largest diapirogen rock salt body in the country.

Historical Exploitation

The first salt exploitations are documented from Roman times, but the mine in Praid is first mentioned in documents from 1200, with intensive exploitation starting in 1700.

Roman Methods

• The Romans worked only at the surface, in square pits, to a depth of 12-15 m, from where salt could be easily extracted on slippery ramps using simple lifting devices.
• After extracting salt, they would abandon the site and start another, leading to abandoned excavations that became lakes.

Volker Wollmann, in his monograph on mining, emphasizes the presence of a Roman fortification near the salt deposits each time. The Roman fort Praetoria Augusta at Inlăceni protected the salt exploitations at Praid.

Modern Developments

In 1980, a treatment facility was opened in the salt mine. Following the extraction of salt, large underground cavities were formed, where a salt mine microclimate was established, with:

• Relatively constant temperatures between 14-16°C
• Low humidity of 66-70%
• Atmospheric pressure higher than at the surface, averaging 735-738 mmHg

The air is highly ionized, particularly effective in treating respiratory conditions.

Treatment Facility

The treatment facility, located at "horizon 50," at a depth of 120 m, has:

• A width of 20 m
• A height of 14 m
• A length of several hundred meters

Over a distance of 1250 m from the entrance of the mine to the treatment facility, transportation for visitors is provided by the mine's buses.

Visitor Amenities

The mine is equipped with:

• Recreational areas
• Playgrounds for children
• A restaurant
• Restrooms
• A chapel for prayer
• An internet café
• A museum showcasing the methods of salt extraction from ancient times to the present day

At Praid Salt Mine, underground speleo- and climatotherapy treatments are conducted as a simple and effective method for:

• Alleviating the condition of patients suffering from respiratory diseases
• Maintaining and restoring mental balance
• Toning the autonomic nervous system

In 2009, Praid Salt Mine was the most visited salt mine in Romania, with over 200,000 tourists annually, followed by Slănic Prahova with over 150,000 tourists, and Târgu Ocna and Cacica Salt Mines.

Source: [Wikipedia](http://ro.wikipedia.org)