An interesting side note is that discarded specimens of nitratine were said to have been thrown into a garden and this is how the importance of nitrates in good plant growth was first discovered. Color is white or gray, sometimes with tints of red-brown or yellow. Luster is vitreous. Transparency crystals are translucent to transparent. Crystals are rare, but when found are in the form of rhombohedrons similar to calcite's crystals.
Cleavage is perfect in three directions forming rhombohedrons.
Fracture is conchoidal. Hardness is 1.5 - 2. Streak is white. Associated Minerals gypsum , halite and other arid region minerals. Deliquescent, slightly sectile, very soluble in water and gives a yellow flame test result.