What is "sulfates"

Usage examples of "sulfates".

Acacia gum, a dairy glue called casein, pink earth, gallic acid, powdered sulfates of green and turquoise, soot, lampblack, red wine, white wine, woad, ground bones, and gesso all modified the pigments in some way: thickening, creating textures, darkening, lightening, and altering color, shine, and absorbency.

Carbonates, sulfates, and nitrates had all been left behind by the slow evaporation of the ancient Martian seas.

Oh, and zinc and copper sulfates to replace the trace elements our system accidentally dumped.