Thursday salt

Production began in the 14th century at the Trinity Lavra of St. Sergius monastery, located near Kostroma. It has had a long tradition in Russia. Today, people use it like regular salt. But it's not good for soups since it is insoluble.[1]

Black salt production had stopped for a while. But some old people in Kostroma remembered how to make it. Now, families make it once a year. They make it for Easter. A group started making more of it in 2000. They made up to 12 tons in a year. This group sells the salt in markets and online.[1]

Thursday salt is produced by mixing rock salt with other ingredients. These can be eggs, flour, or rye bread. Some add cabbage leaves or herbs like thyme. They wrap this mix in linen cloth. Then, they bake it on birch wood in a special oven. The oven is very hot, up to 600°C. The mix melts and forms a lump. This lump is left in the oven for many hours. After that, they grind the lump. They remove the ash. What remains are the black salt crystals.[1]

To make Thursday Salt, white rock salt is heated until it blackens. It's then cooled and ground into powder. Any remaining coal dust is removed.[2]

Three traditional recipes are used:[2]

1. Kvass mixed with salt, charred in a pot.[2]
2. Rye bread with herbs and salt, charred and ground.[2]
3. Oatmeal blended with salt, charred similarly.[2]

Heating changes the salt. The rye ash adds minerals to the salt. These minerals include calcium and potassium. The salt also becomes looser. It doesn't absorb moisture easily.[1]

The salt is traditionally blessed at Easter and used with festive foods. It can also be blessed at home.[2]

It is occasionally used in spiritual rituals.[6][3][4]

• Black lava salt
• Himalayan salt
• Jugyeom
• Kala namak