Colourless, yellowish, greyish, white; colourless in transmitted light
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
1.991
Crystal System:
Monoclinic
Name:
Named in honor of Joseph Louis Gay-Lussac (6 December 1778, Saint-Léonard-de-Noblat, Kingdom of France - 9 May 1850, Paris, France), French chemist and physicist. He co-discovered that water is made of two parts hydrogen and one part oxygen and also discovered two laws of gasses. He co-discovered the element boron and recognized iodine as a new element (and named it). In some older publications, the mineral name is written as gay-lussite, with a hyphen.