Tavush Green Earth Pigment
A green earth (celadonite) pigment known as terre verte from mineral deposits in Armenia. Learn more.
Rublev Colours Tavush Green Earth is the greenish mineral celadonite—a phyllosilicate of hydrated iron potassium silicate containing small amounts of aluminum, calcium, magnesium, sodium, and numerous trace elements. It is a green mineral that looks like tiny flakes of the mineral mica or small lumps of clay. The color of celadonite varies considerably from pale green, bright green, bluish-green, olive-green, and black-green, depending upon its constituent elements. Rublev Colours Tavush Green Earth is from the Idzhevanskoe deposit, Idzhevan, Tavush province of Armenia.
|Common Names:||English: green earth|
French: terre verte
Italian: terre verde
Spanish: terra verde
|Mineral Names:||English: celdadonite|
Origin and History
The word celadonite is derived from the French word celadon, meaning sea green. It has been in painting since ancient times, found recently on Roman frescoes. Restorers have proved through X-ray diffraction that the famous pigments of past centuries known as Veronese terre verte are, in essence, celadonite minerals. It was first described in 1847 on Monte Baldo, near Verona, Italy. It is one of two minerals, along with glauconite, used in making the pigment green earth.
Celadonite is almost exclusively found associated with basic-eruptive rocks in deep-marine environments. Altered basalts from ocean-bottom environments that contain celadonite have been found. Basalts containing celadonite can also be found on dry land, but these are usually assumed to have originated from marine environments.
Green earth pigments, also known as terre verte, form a dull green color in their dry powder. They are inorganic pigments composed of the minerals celadonite and glauconite. However, according to Anne Wall Thomas, “Green earth, or terre verte, is a mineral but not in the strictest sense an iron oxide pigment. Consequently, it cannot be classified as a product of one of the four iron ores. The presence of celadonite or glauconite, minerals of complex silicate composition, produces colors that vary from cold bluish greens to warmer yellow and olive hues. The green earths, which contain small amounts of iron along with manganese and other components, may have origins in oceanic deposits.” (Thomas, 12–3)
Anne Wall Thomas (1980) Colors from the Earth: The artist’s guide to collecting, preparing and using them. Van Nostrand Reinhold Co.
The particle size composition of Tavush Green Earth is 80–85% from sub-0 to 15 microns, with the remainder ranging up to 30 microns with only 0.1% at 30 microns and above.
Permanence and Compatibility
Green Earth is among the most permanent colors in the artist’s palette. It is compatible with all other pigments and can be used with good results in all mediums.
Oil Absorption and Grinding
This pigment is easy to grind in vegetable drying oils and water. The oil absorption value (OAV) is 28 grams of linseed oil for 100 grams of pigment.
The pigment is considered non-toxic, but care should always be exercised when handling the dry powder pigment to avoid inhaling the dust.
Rublev Colours Pigment: Tavush Green Earth
|Color Index:||Pigment Green 23 (77009)|
|Chemical Name:||Phyllosilicate mineral|
|Chemical Formula:||K(Mg,Fe2+)(Mg,Fe3+, Al)+[Si4O10](OH)2|
|ASTM Lightfastness Rating|
|Oil Absorption:||28g oil / 100g pigment|
|Bulk Density:||2.95–3.05 g/cm3|
|Refractive Index:||nα = 1.606–1.625 nβ = 1.630–1.662 nγ = 1.579–1.661|
|Heat Stability:||320° C|
|Water Solubility:||< 0.18%|
|Silicon Dioxide (SiO2)||63.66|
|Aluminum Oxide (Al2O3)||16.36|
|Titanium Dioxide (TiO2)||0.69|
|Iron Oxide (Fe2O3)||7.08|
|Manganese Oxide (MnO)||0.09|
|Calcium Oxide (CaO)||2.32|
|Magnesium Oxide (MgO)||1.81|
|Chromium Oxide (Cr2O)||–|
|Potassium Nitrate (K2O.N2O3)||5.20|
|Processing Time||Usually ships the next business day.|
|Pigment Type||Inorganic, Natural|