Definition: To give you an idea of the variety of these materials some of the phases we have encountered in scales include, calcite, Mg-calcite, aragonite, Sr-Ca-carbonate, dolomite, siderite, gypsum, anhydrite, barite, Sr-barite, celestine, halite, berthierine, pyrite, and sphalerite although this list is not exhaustive.   Clearly various carbonates and sulphates are common, and often they are non-stoichiometric.

Celestine scale

Analyses: X-ray diffraction (XRD) is the primary technique for the identification of scales.  Precise measurement of peak positions can also give information on the solid solution compositions of non-stoichiometric scale phases, such as an estimation of the Sr-content of barite.