The turquoise group consists of five triclinic minerals. These minerals are very similar in chemical composition, crystal structure, physical properties and often in appearance. Members of the group are: turquoise, aheylite, chalcosiderite, faustite, and planerite. Their compositions are listed in the accompanying table.

Notice that the members of the turquoise group have very similar chemical compositions. In these minerals iron often substitutes for aluminum, and copper often substitutes for zinc or iron. Because they are so similar and have ranges of composition, these minerals are often misidentified. As a result, some material sold as turquoise is actually another mineral member of the turquoise group.