English: blue amphibole, blue asbestos, blue Cape asbestos, Crocidolite (variety)
Origin and History Riebeckite is a not well-known dark blue mineral although most people have probably seen stones that at one time were composed of riebeckite crystals. The mineral was named after a famous 18th-century German explorer and mineralogist, Emil Riebeck (1853-1885). The mineral was identified on wall paintings on Crete (Knossos, Ayia Triada, Amnissos), mainland Greece (Mycenae) and Cyprus (Akrotiri and Thera), and other works of art since Late Neolithic times (at least the 4th millennium B.C.E.) and the Early Bronze Age, where its was used alone and in combination with Egyptian blue (a synthetic blue pigment).
Source Riebeckite is a natural silicate mineral belonging to the amphibole group with notable occurrences in Soqotra, South Yemen; Transvaal, South Africa; Schirmeck, Germany; Langesund, Norway; Krivoi Rog, Ukraine; Western Australia; Scotland; Madagascar; and the USA. Rublev riebeckite pigment is made from deposits in Krivoi Rog, Ukraine. Some forms of riebeckite are asbestiform and can be used as asbestos. Asbestos has many industrial uses despite some health risks and is made of different minerals all with a fibrous habit. Riebeckite has a variety called “crocidolite” that is asbestiform in habit, which is the mineral variety of the Rublev pigment.
Permanence and Compatibility Riebeckite is not affected by light and is stable under normal atmosphere. It is resistant to alkalis and hence can be used in fresco and casein.
Oil Absorption and Grinding Riebeckite absorbs a moderate amount of oil (20 g oil per 100 g of pigment).
Toxicity Riebeckite is an asbestiform mineral and is rated toxic, especially with prolonged exposure by inhalation. It is not considered toxic in contact with the skin. Asbestos is a known carcinogen. Care should be used in handling the dry powder pigment to avoid breathing the dust. A NIOSH-certified dust mask should be worn.
Sodium Iron Magnesium Silicate Hydroxide
ASTM Lightfastness Rating
3.2–3.4 (3.2 g/cm3)
a=1.68-1.698, b=1.683-1.7, g=1.685-1.706
20 g oil/100 g pigment
California Proposition 65: This product contains a chemical known to the State of California to cause cancer and birth defects or other reproductive harm.
Color: Dark Blue Chemical Name: Sodium Iron Magnesium Silicate Hydroxide Acrylic: Not rated Oil: Not rated Watercolor: Not rated Hardness: 5–6 Refractive Index: a=1.68-1.698, b=1.683-1.7, g=1.685-1.706 Oil Absorption: 20 g oil/100 g pigment
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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