/ ree • al • gar /

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How Realgar is made:

Origin: mineral and artificial Realgar (at Mineralogy Database)

Realgars is found throughout the world in hot-spring deposits, volcanic sublimation, and in certain limestones and dolomites.

Natural variety of pigment Mineral azurite is simply ground, washed, and sieved. Coarsely ground azurite produces a dark blue, while finely ground azurite produces a lighter tone.
Artificial variety of pigment
Numerous early recipes for the preparation of basic copper carbonate are knownfrom the 17th century; the best types appear to have been prepared at relatively low temperatures with a copper salt. This sky blue, slightly more greenish than natural azurite, lends itself well to consistent applications of color. Microscopically, blue bice appears as tiny, rounded, fibrous aggregates, even in size and blue by transmitted light. It is similar in color to finely ground azurite.
19th century recipe Dissolve the copper, cold, in nitric acid (aquafortis), and produce a precipitation of it by means of quicklime, employed in such doses that it will be absorbed by the acid, in order that the precipitate may be pure oxide of copper, that is, without any mixture. When the liquor has been decanted, wash the precipitate and spread it out on a piece of linen cloth to drain. If a portion of this precipitate, which is green, be placed on a grinding-stone, and if a little quicklime, in powder, be added, the green color will be immediately changed into a beautiful blue. The proportion of the lime added is from 7 to 10 parts in 100. When the whole matter acquires the consistence of paste, desiccation soon takes place.
In the lab



The ground pigment:

Pile of ground Realgar