Much of southern Saskatchewan is underlain by the Prairie Evaporite Formation, a layered sequence of salts and anhydrite which contains one of the world’s largest deposits of potash. The 100 m to 200 m thick Prairie Evaporite Formation is overlain by approximately 400 m of Devonian carbonates followed by 100 m of Cretaceous sandstone, 400 m of Cretaceous shales, and 100m of recent Pleistocene glacial tills to surface. The Prairie Evaporite Formation is underlain by Devonian carbonates. The Phanerozoic stratigraphy of Saskatchewan is remarkable in that units are flat-lying and relatively undisturbed over very large areas. Potash mineralization in this region of Saskatchewan is predominantly sylvinite, which is comprised mainly of the minerals sylvite (KCl) and halite or rock salt (NaCl), with trace carnallite (KMgCl3 · 6H2O) and minor water insolubles. Potash fertilizer is concentrated, nearly pure KCl (i.e. greater than 95% pure KCl), but ore grade is traditionally reported on a % K2O equivalent basis. The “% K2O equivalent” gives a standard measurement of the nutrient value of different potassium-bearing rocks and minerals. To convert from % K2O equivalent tonnes to actual KCl tonnes, multiply by 1.58.

There are three mineable potash members within the Prairie Evaporite Formation of Saskatchewan. Stratigraphically highest to lowest, these members are: Patience Lake, Belle Plaine, and Esterhazy. The Cory potash deposit lies within the Patience Lake Potash Member of ........

At Cory, potash ore is mined using conventional mining methods, whereby:
- Shafts are sunk to the potash ore body;
- Continuous mining machines cut out the ore, which is hoisted to surface through the production shaft;
- Raw potash is processed and concentrated in a mill on surface; and
- Concentrated finished potash products (near-pure KCl) are sold and shipped to markets in North America and offshore.

Sinking of the two original shafts (Shaft #1 and Shaft #2) from surface to the potash zone was completed in 1968, and the first potash ore was hoisted in the fall of that year. The Cory mine has run on a continuous basis since the first ore was hoisted in 1968, other than short-term shutdowns taken for inventory management purposes or occasional plant maintenance and construction work.

Virtually all Cory underground mining rooms are in one potash mineralized zone, the upper layer (or A Zone) of the Patience Lake Member of the Prairie Evaporite Formation (the host evaporite salt). In contrast, some potash mines further east in Saskatchewan mine in a different potash layer, the Esterhazy Member of the Prairie Evaporite Formation. At Cory, mine elevations average approximately 1,010 m depth below surface. Mine workings are protected from aquifers in overlying formations by approximately 12 m of overlying salt and potash beds, along with salt plugged porosity in the Dawson Bay Formation, a carbonate layer lying immediately above potash ........

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