In mineralogy, native vitriol is a substance of a grayish or yellowish white color, apple green, or sky blue, and when decomposed, covered with an ochery crust. It occurs in masses, disseminated, stalactical, or capillary. Externally, it is dull and rough; internally, it is more or less shining, with a vitreous silky structure. It is called by manufacturers copperas, a name derived from the flower or efflorescence of copper. This substance is seem only in cabinets.

In chimistry, a combination of the acid of sulphur with any metallic substance; but chiefly green vitriol, or sulphate of iron; blue vitriol, or sulphate of copper, and white vitriol, or sulphate of zink. All metals may be converted into vitriols, by dissolving them with acid spirits, and suffering them to stand and crystallize.