In dolomitic limestone and limy shale.
The main salt bed is 8.2 m thick and is at a depth of 289 m to 297 m below the surface. Another bed is 9 m above it. The salt is exceptionally pure containing less than 2 per cent impurities. The salt beds occur in the Salina Formation of Silurian age.
The salt bed was discovered by Canadian Rock Salt Company as a result of diamond drilling carried out in 1952. A production shaft was sunk to a depth of 335 m. The mine workings extend beneath the Detroit River. Due to water conditions (aquifers) and hydrogen sulphide gas, the ground had to be frozen to a depth of 229 m by a series of freeze-holes drilled 1 m along the circumference of a circle 9.7 m in diameter prior to shaft sinking. Production began in 1955.
| Anhydrite|| Halite|
2 entries listed. 2 valid minerals.
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Locality Updated: A 6 road cut, Elvas, Portalegre District, PortugalFrom Rui Nunes, 11th Dec 2013 21:48:46