GaylussiteIs a mineral formed in desertic areas ,where the rich salt water precipitates and forms crystals ( evaporite ) The formula is Na Ca (Co3)2 *5H2O , a hydrated calcium sodium carbonate. Is also unstable and can be dehydrated in air and dissolve in water. The hardness  H2.5 This gem comes from Searles Lake ,California . A collectors item, rare to be find in faceted gem. Small visible inclusions. Size: 21.5x7.9x5 mm. Weight: 4.10 ct.

the world rarest Stone