Alternate Names: Volchonskoite, Wolchonskoite Color: Green Colour Index: Not Listed ASTM Lightfastness: Not tested Density: 2 Hardness: 2-2.5 Chemical Formula: Ca0,3(Cr+3,Mg,Fe+3)2(Si,Al)4O10(OH)2*4H2O
A chromium-bearing mineral that is part of the smectite group, volkonskoite is a clay mineral found in sandstones, conglomerates, and red beds, commonly filling voids from the decomposition of organic material. The largest deposit of volkonskoite is found in Mt. Efimiatsk and elsewhere in the Okhansk region, Middle Kama River area, Perm Basin, Ural Mountains, Russia. We get our pigment from mineral sources near the village of Efimiata in the Perm Basin. The pigment was named for Prince A. Volkonskoi, Minister of the Imperial Court, Russia, in the 19th century. Its masstone varies from olive green to bright emerald green. Ours is a deep forest green edging towards an olive green. Usually the mineral is free from impurities and is ready for use as a pigment without much preparation.
History of Use: There is little known about the use of this pigment in ancient art. There is some evidence of a green chromium oxide pigment in some European works from the Renaissance. Pablo Picasso especially liked this pigment, which he imported from the former Soviet Union.
Permanence and Compatibility: Volkonskoite is considered to be a permanent pigment. It is unaffected by exposure to light. There are no known incompatibilities with other pigments and paint binders.
Oil Absorption and Grinding: No data has been published on the oil absorption properties of volkonskoite. A unique characteristic of the mineral volkonskoite is its high adhesive property, which complicates pulverizing it for use as a pigment. One method to eliminate this difficulty is to add a small amount of quartz to volkonskoite while grinding or mulling the mineral. The addition of quartz does not detract from its qualities as one of best green pigments to use in glazes.
Toxicity: Volkonskoite is somewhat toxic and care should be used in handling the dry powder pigment so as not to inhale its dust.
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