Ultramarine blue, natural
Natural ultramarine blue pigment is the ground, separated blue particles (lazurite) from the gemstone lapis lazuli. Lapis has been mined since the 3rd millennium BCE in Afghanistan at the Badakhshan mines. Ancient trade routes distributed the lapis throughout Europe and the Far East. From the 13th century, the method used to prepare ultramarine pigment mixed powdered lapis with wax, resin and oils then kneaded the mixture in a dilute lye solution; this allowed the blue particles to disperse into the alkaline water while the extraneous minerals (e.g., calcite, pyrite, silicates) are retained in the putty. This was a time consuming process that produced varying shades of blue. The purest, deep blue was extracted in the first batch and sold for very high prices. As the process was continued, the subsequent batches of pigments were slightly less pure; the final batch was a transparent blue gray called ultramarine ash. In all the fractions, some transparent material is present (calcite) which aids microscopically in the distinguishing the natural from synthetic ultramarine pigments which were first made in 1828. Ultramarine blue is used as a pigment in paints (oil, tempera, watercolor, fresco), wallpaper, soap, textile printing, and laundry bluing agents.
Synonyms and Related Terms
natural ultramarine blue; Pigment blue 29; CI 77007; lapis lazuli blue; Ultramarinblau, echt (Deut.); outremer naturel (Fr.); blu oltremare naturale (It.); lapislazzuli (It.); ultramarino verdadero (Esp.); lapislázuli (Esp.); oyltramarina fysikh (Gr.); lapis lazuli (Gr.); ultramarijn blauw (Ned.); ultramaryna (Pol); ultramarin (Sven.); azul ultramarino, natural (Port.); bleu d'Azur; Armenian blue; lazuline blue; ultramarine ash; mineral blue; vein stone; lazurstein
Discolors when exposed to weak acids or sulfur fumes.
Irregular particles, no birefringence, no pleochroism, extinction under crossed polars. Naturally mixed with silicates, calcite and pyrite.
Insoluble in water. Isotropic crystal system.
ASTM lightfastness=1 (excellent)
|Density||2.4 - 2.5|
|Refractive Index||about 1.5|
Hazards and Safety
No significant hazards. Noncombustible.
Becomes dull with outdoor weathering.
° J. Plesters, "Ultramarine Blue, Natural and Artificial", Artists Pigments, Volume 2, A. Roy (ed.), Oxford University Press: Oxford, 1993.
Sources Checked for Data in Record
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