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Azurite or Azure spar [5]: 14 is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite , after the type locality at Chessy-les-Mines near Lyon , France . [ 3 ]
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.
Azurite was frequently used in European Renaissance painting. It appears, for example, in the dark blue sky of a Spanish altarpiece painting by Bartolome Bermejo. [8] In this painting, azurite is also combined with lead white to paint the green robe of the Saint. [8] During this time, azurite was a common pigment used to paint a blue sky. [1]
Azurmalachite is a mixture of azurite and malachite. [1] It is alternatively called azuromalachite, azurite-malachite and malachite-azurite. [2] Azurmalachite has a distinctive mottled green and blue coloration. It is relatively rare but can sometimes be found above copper deposits.
Associated minerals are quartz, limonite, azurite, malachite, cuprite, and other secondary copper minerals. It is typically found as botryoidal or rounded masses and crusts, or vein fillings. A 2006 study has produced evidence that chrysocolla may be a microscopic mixture of the copper hydroxide mineral spertiniite , amorphous silica and water.
Malachite and azurite are attractive, richly colored copper hydroxy-carbonate minerals. Malachite has a nice green color - its formula is Cu2CO3(OH)2. Azurite has a dark, rich blue color - its formula, Cu3(CO3)2(OH)2, is very close to malachite. The blue color of azurite is from Cu+, while the green color of malachite is from Cu+2.
Lazurite, old name Azure spar [7]: 14 is a tectosilicate mineral with sulfate, sulfur and chloride with formula (Na,Ca) 8 [(S,Cl,SO 4,OH) 2 |(Al 6 Si 6 O 24)].It is a feldspathoid and a member of the sodalite group.
Fine-ground azurite produces a lighter, washed-out color. Traditionally, the pigment was considered unstable in oil paints, and was sometimes isolated from other colors and not mixed. The use of the term spread through the practice of heraldry , where " azure " represents a blue color in the system of tinctures .