Azure spar | |
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General | |
Category | Mineral |
Azure spar, sometimes azur-spar (German: Lazur spath, Blau spath) is a trivial and commercial, partly obsolete name for several of the most famous bright blue or blue-colored minerals, which also have similar names, most notably for lazurite and azurite,[1]: 14 and also for the less commonly used lazulite.[2]: 248
In addition, Robert Jameson in his fundamental works of 1804-1821 also included hauyne as a separate mineral species[3] and the so-called “calaite”, which in the 1820s meant only turquoise, among the azure feldspars.[4]: 571–572
All of the listed minerals are known primarily as ornamental stones, and have historically been used as painting pigments and dyes for various purposes. More than others, lazurite or lapis lazuli has historically had a decorative use, classified by A. Fersman and M. Bauer as a first-order semi-precious ornamental stone. Haüyne is valued significantly higher than lapis lazuli, but it is rarely found in jewelry quality suitable for cutting. Azurite or copper azure is much less often used as an ornamental stone due to its fragility and chemical instability, but this mineral has been known since ancient times as a pigment for blue tempera paint, mainly in icon painting. Finally, lazulite is sometimes used not only as an ornamental stone, but also for jewelry cutting, although finds of high-quality raw materials are too rare for its mass use. As for turquoise, it has been one of the most popular ornamental and semi-precious stones since ancient times.