Jarosite is a yellow-colored, hydrous sulfate of iron and potash mineral occurring in sulfurous layers of iron ore. The color of the mineral is amber yellow, but sometimes brownish-yellow. Our jarosite is from the Zhuravlinskogo deposits in Perm, Russia, and is a bright golden yellow that is opaque, exhibits good covering power and works well in all medium.
Origin and History Previously not known as a historical pigment, jarosite was recently identified as the yellow pigment in the murals of the temples of Karnak, Egypt.
Source Jarosite, named in 1852 after the typical locality of its discovery, Barranco Jaroso, in southern Spain. It is a hydrous sulfate of iron and potash mineral occurring in minute rhombohedral (actually a combination of two trigonal pyramids) crystals. Jarosite crystals are somewhat scarce and small. The mineral is more commonly encountered as earthy masses, films or crusts, botryoidal and granular. It is formed during the weathering of sulfurous layers of iron ore. Jarosite is an uncommon mineral, yet it is present in small quantities in almost all layers containing iron sulfides. It is often associated with barite, turquoise, galena, goethite, limonite, hematite and other iron minerals. Notable occurrences of jarosite include the Jaroso ravine, Sierra Almagrera, Spain; Iron Arrow Mine, Colorado; and Maricopa County, California, U.S. In the former Soviet Union, deposits of jarosite are found in the Achi-Say layers of Kazakhstan and Zhuravlinskogo in the Perm region of Russia. We obtain our jarosite pigment from the Zhuravlinskogo deposits in Perm, Russia.
Permanence and Compatibility The sulfate content of iron oxide pigments rarely exceeds one percent, yet in the mineral jarosite sulfides can be as much as 25 to 35% of its composition. Although sulfide pigments have been known to be unstable, a study by K. I. Tolstikhinoy showed that jarosite is resistant to atmospheric gases, is lightfast and possess good hiding power.
Oil Absorption and Grinding Jarosite absorbs a moderate amount of oil during dispersion and forms a good flexible film.
Toxicity Jarosite is not considered toxic but care should be used in handling the dry powder pigment so as not to inhale the dust.
Pigment: Yellow Jarosite
Potassium Iron Sulfate Hydroxide
ASTM Lightfastness Rating
Color: Yellow Color Index: Not Listed Chemical Name: Potassium Iron Sulfate Hydroxide Acrylic: Not rated Oil: Not rated Watercolor: Not rated Density: 3.2 Hardness: 2.5–3.5 Refractive Index: 1.713–1.820
Natural Pigments is a limited liability company based in Willits, California. We manufacture and distribute rare and hard-to-find materials for fine artists and decorators. We specialize in supplying artists' materials that were used in historical painting since pre-historic times up to and including the nineteenth century.
We constantly search for materials and products of the finest quality so that we can bring them direct to you from the source. To do so, we travel the world to find materials specifically for use by professional artists and decorators. We obtain minerals from mines in Afghanistan, Chile, Russia, Ukraine and Uzbekistan, to name a few places, processing these into natural pigments. We purchase resins, gums and plants from India, Kenya and Malaysia to make natural varnishes and painting mediums.
Our mission is to provide the largest variety of natural pigments, paints and other professional artists' supplies, enabling us to bring you a selection that makes shopping for rare and hard-to-find art materials easy. Our objective is to promote the education and use of these materials among artists by providing detailed information for their employment in encaustic, fresco, oil, watercolor and tempera painting.
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