Azurite, Azurro della Magna (d'Allemagna), Mountain blue, Blue copper, Chessylite
Natural pigment suitable for icon painting (egg tempera), oil painting and watercolor painting without additional grinding.
Azurite, is a natural basic copper carbonate. This mineral is a secondary copper mineral frequently found in the oxidized zones of copper bearing ore deposits around the world. Azurite is found in over 40 forms of blue colored ore. These include tubular prismatic crystals that form small roses of a deep beautiful azure blue color. Azurite is often pseudo-morphed to a green mineral, malachite, and the two are always found together.
Azurite has been used as a pigment as early as the Fourth Dynasty in Egypt. Azurite was no doubt the most important blue pigment in European painting from the fifteenth to the middle of the seventeenth century. The paintings of that period of time commonly contain more azurite than natural ultramarine (lapis lazuli). Often the two were used together in paintings, with the solid colored and cheaper azurite pigment in under-painting with the transparent natural ultramarine in glazes.
The invention of the Prussian blue pigment in the eighteen century caused the disappearance of natural azurite colors from the painter's palette.
Azurite, when correctly prepared, is the most permanent pigment known. Its bad reputation of morphing its color to green, or darkening, comes from the incorrect application of size, as a binder, to hold bigger particles firmly in place. It's known that size is easily affected by moisture and turns dark, but pigment particles are unaffected. Incorrect restoration techniques in the past are the cause of discoloration too. Azurite never changes in mixtures with lead white.
Our minerals come from Jiangxi location in China. Their mines are a good source of the best grades of the almost depleted mineral. It's hard to find this blue mineral in a quality suitable for artistic use.
The pigment preparation starts with hand selection and the cleaning of the raw geological specimen, that often includes grinding off impurities from it by hand. Because of the wide variety of azurite forms and colors, the materials are separated into different grades. Then each grade is resized by the jaw crusher into rough sand. The sand is then washed, and the milling in water follows. Gradual milling is done in a high alumina ceramic ball mill with zirconia media. This is a virtually contamination-free milling preparation. Azurite is soft mineral (3.5-4 Mohs scale) so the contamination from milling is negligible. The solution of water and pigment particles of various sizes are the result of milling and are then left to settle. In 10 to 30 minute intervals the solution is poured into different containers. Settled pigment is collected and washed in water over and over until the PH of the water is neutralized, then is left out to dry. The dried pigment is then sieved and separated by particle size.
The next step of cleaning is done in a weak solution of water and egg yolk. The egg yolk solution binds with impurities from the pigment. The color of the mixture turns grayish blue and keeps impurities afloat in a whitish sludge while clean pigment particles drop to the bottom of the container. This process also slows down sedimentation and helps separate the pigment into fine grades. The fine pigment prepared by this method is free of unstable particles, doesn't require additional milling and produces fine shades of this unique blue color.