Calcium nitrate, also called Norgessalpeter (Norwegian saltpeter), is the inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula Ca(NO₃)₂. This colourless salt absorbs moisture from the air and is commonly found as a tetrahydrate

Water of crystallization

In crystallography, water of crystallization or water of hydration or crystallization water is water that occurs in crystals. Water of crystallization is necessary for the maintenance of crystalline properties, but capable of being removed by sufficient heat...

. It is mainly used as a component in fertilizer

Fertilizer

Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

s but is found other applications. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence

Efflorescence

In chemistry, efflorescence is the loss of water of crystallization from a hydrated or solvated salt to the atmosphere on exposure to air.-Examples:...

 where manure

Manure

Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...

 contacts concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 or limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 in a dry environment as in stables or caverns.