The Brentonico green earth is a natural inorganic mineral pigment, known since ancient times and widely used in the classical and Renaissance ages. Its processing includes purification, drying and grinding with ball mills of the raw material available in the Verona area.
In particular, the minerals from which it is obtained are glauconite and celadonite, both belonging to the micas group. These minerals were formed by alterations of minerals in not very deep marine waters or in volcanic rocks.
Glauconite in particular is a mineral of marine depositional environment and derives from the marine diagenetic alteration in relatively shallow waters and in reducing conditions of biotite. Glauconite has long been used in Europe as a green pigment for artistic oil painting under the name of green earth. An example is its use in Russian “icon paintings”, another widespread use was for background painting of human flesh in medieval painting. It is also found as a mineral pigment in wall paintings of ancient Roman Gaul.
Celadonite, on the other hand, was first found in 1847 on Monte Baldo, near Verona, in Italy. The name derives from the French celadon, referring to the teal color.
Together the two minerals are used to make the earth pigment green.
EXTRACTION METHOD The processing of the green coloring earths, after they have been extracted from the quarries and dried, differs from type to type; some are coarsely crushed, separated from impurities, ground with hammer or ball mills. The processing of the lands that form the green Brentonico includes purification, drying and grinding with ball mills. CURIOSITY The pigment was already known to the Greeks and Romans and was used in all pictorial techniques during the Middle Ages and the Renaissance until the 19th century. In ancient times it was reserved only for the nobles, while today it is highly sought after in the artistic field for its characteristic semi-transparency. Due to its chromatic beauty, celadonite or, precisely, "green earth of Monte Baldo", became the reference standard of the pigment widely used in painting especially in frescoes, to the point that even today it is cited in the catalogs as "Verona green ” or “green of Brentonico”. Among the many great artists who also made use of it, that of Caravaggio is particularly documented. With ups and downs starting from the sixteenth century, large quantities were extracted in the mountain mines of Trett and Pianeti di Val Aviana on Monte Baldo which were marketed in Italy, Europe and America. The mines of "green earth of Monte Baldo" made the economic fortune of the Eccheli lineages up to the eighteenth century and then of the Baisi until the early twentieth century