During the earth's formation, the Guérande salt ponds in Brittany, northwestern France , were part of a bay in the  Atlantic Ocean . The gradual retreat of the sea left behind a series of floodable pools.
By the Middle Ages, the ocean had tried to reclaim its territory, but man had already modeled the landscape to extract  the "white gold". Between 1540 and 1660, the salt pond area was definitively established and salt from Guérande was in demand and traveled all over the world.
A gigantic mosaic of salt ponds, the Guérande peninsula retains and subdues the ocean's tides. The twofold action of the sun and the wind bring into existence sea salt, a completely natural and unprocessed source of elements trace and taste.

Two kinds of sea salt are produced in the ponds: Coarse Gray Sea Salt and Sea Salt Blossom.
"GROS SEL" or Coarse Gray Sea Salt
These salt crystals are formed on the bottom of the salt pond. Using a large rake-like tool, the salt gatherer detaches the crystals which he will eventually haul out of the water and pile into a pyramid shape to dry.
Each salt pond section can produce approximately 50 kg per day.
We recommend coarse salt as a replacement for ordinary salt in cooking. In France , table salt as we know it is rarely found. The more natural and highly salting coarse salt is used both in home cooking and fine cuisine by professional chefs.

When the wind blows from the east, fine crystals form on the surface of  the salt pond, forming "Fleur de sel" or what we  call "sea salt blossom" in English. This is the very top of the line, the best salt on the planet. Several grains suffice for flavoring an individual serving.
When harvested, "fleur de sel" is pale pink color. It becomes white after drying naturally in the sun. The salt gatherer harvests it with a  special rake.
Sea salt blossom with its subtle taste of violets is wonderful used at the table to replace ordinary table salt.

Seawater contains about 30 grams (average value) of dissolved salt per litre and to obtain the crystallization should be gradually exceed the level of saturation which is located at 270 grams per litre. To simplify it must be evaporated about 10 litres of 11 before producing on 1 gram. When the salt is enough (25 kg minimum) is extracted by using a raclette called "Las", then reassembled on the "Ladure" or it drips a few hours before being transported on "Trémet" to be the mulon ..

"Eyelets" therefore occupy the remaining 10%, it must be well designed, their ground carefully levelled and compacted. They are surrounded by canals that bring water saturated and others who escaped the waters mothers (and rain). Depending on the weather conditions where the harvest is done once or twice a season or every day.

The first salt deposits which are limestone and dolomite from a concentration of NaCl 30g/litre.

Then the calcium sulfate form hydrated: gypsum. The precipitation starts at a density of 1,109 at a concentration of 150g NaCl / litre.

80% of this salt is crystallized when does the crystallization of sodium chloride d = 1,216, representing a concentration of 350 g NaCl / litre. In the salt marshes precipitation is voluntarily halted when density reached 1,262, for example, brine then contains 40 g / l of magnesium.

The salt crystallizes beyond is bitter and evaporation becomes too slow. The waters are evacuated. To produce 1 kg of salt it takes about 37 kg of sea water which 90% have evaporated before crystallization, 7% during the crystallization and 3% water mothers are dismissed.