Green earth
As green earth fine friable minerals are seladongrüner (sea green) color denotes that since ancient times as earth colors used in the painting. The color can also change into blackish green, gray green or mountain green. They are silicates colored by iron oxide (FeO) .
The green earth in the narrower sense ( Veronese green ) essentially corresponds to the mica mineral celadonite , a greasy, almond-shaped or coated layered silicate with a hardness of 1 to 2 and a density of 2.9. The decomposition product of augite and hornblende contains 41 to 51 percent silica, 3 to 7 percent clay , 21 to 23 percent iron oxides as well as lime, magnesia, alkalis and water. The most famous occurrence on Monte Baldo near Verona was already used by the Romans as a green dye and for water colors. It has also been mined for a long time in Cyprus , near Kadaň in the Czech Republic and in basaltic almond stones in Iceland and the Faroe Islands.
Formations of glauconite , a mica mineral from blue-green to yellow-green in color, are also referred to as green earth . It forms small, round grains a few tenths of a millimeter in size, which have grown into clay, marl or sandstone or are connected to form loose, easily friable aggregates. It consists of water-containing silicate of iron oxide and potash (the latter usually 5 to 15 percent) with a few percent alumina. Green limes and marls containing glauconite are known in the Silurian mountains of Sweden and Russia, in the chalk marls in Saxony and the Czech Republic and in the chlorite chalk of Rouen.
Green sands and green sandstones are also common in chalk formations, especially in the lower and middle chalk of France and England, as well as in the chalk of Westphalia, the Czech Republic and New Jersey. However, green sands also occur in the Tertiary Mountains, for example in the Alpine Eocene, in the so-called Nummulite Mountains and in the Samland . In southern England and New Jersey, Cretaceous greensand containing 6 to 7 percent potash is used as an effective fertilizer.
In chalk rocks and marls, green earth is a common filling compound of foraminiferous shells . They are used (stone green, Veronese green, Veronese earth, French green, etc.) mainly as paint, also in oil and water painting and because of their durability in fresco painting. The Veronese green earth is highly green and quite firm, the Cypriot apple to chip green and softer, the Polish leek green and mixed with sand, the Tyrolean and Bohemian pale green.
