Green Earth Pigment

Green earth, known in Italian as terra verde and in French as terre verte, is one of the oldest, most versatile, and most stable pigments in the history of painting. Compatible with all techniques and binders, it was prized by generations of artists for its beauty and delicate transparency, which made it the ideal choice for cool undertones in flesh painting. Lightfast, inexpensive to prepare by simple crushing and grinding, and unreactive with lime plaster, green earth remained a staple of the painter’s palette from antiquity to the present day.

Cennino Cennini describes green earth in Il Libro dell’Arte (Chapter LI) as a natural earth color, noting that it is a very fat, full-bodied pigment, suitable for painting faces, garments, and buildings, in fresco, secco, on walls and on panel. He specifies that it should be ground with clear water, and that the finer it is ground, the better it becomes. Cennini also records that green earth served as a bole for gilding on panel, noting that the ancients used nothing else for gilding on panel but this green.

The use of green earth as a pigment is documented from antiquity. Vitruvius (1st century BCE) mentions creta viridis, noting that the Greeks called it Theodotian after the estate where it was first found. Pliny describes Appian green as a cheap imitation of malachite made from green earth. The pigment was identified among the earliest sets of pigments technically examined, in jars from a shop at Pompeii and in Roman wall paintings, where it was particularly favored for fresco because it does not react with lime plaster.

In the medieval period, green earth became widely used in tempera painting, most famously as the undertone for flesh on panel. Cennini describes the technique in Chapter CXLVII: a thin layer of green earth mixed with a little lead white is applied over the entire area of the face, hands, and feet before the flesh colors are built up on top. On walls, Cennini describes using verdaccio, a mixture of black, ochre, and lime white, in place of green earth for the same underpainting role, likely due to the lower cost of this mixture. Over this base in fresco, thinned green earth is used to shade under the chin, along the sides of the mouth, under the nose, and around the eyes, and Cennini specifies that the green must always show through a little beneath the pinkish layers of flesh color.

Andrea Pozzo, writing in the late 17th century, singled out Verona green earth as la più bella, anzi l’unica (the most beautiful, indeed the only one) suitable for fresco, noting that most other greens are artificial and incompatible with lime.

Green earth pigment is composed principally of celadonite or glauconite, two closely related iron-bearing phyllosilicates of the mica group. Its green color arises from the interaction of ferrous (Fe²⁺) and ferric (Fe³⁺) iron within the layered silicate structure. The pigment is characteristically low in chroma, translucent, and warm in tone, ranging from a grayish blue-green (celadonite-rich earths) to a more yellowish green (glauconite-rich earths).

The two principal minerals differ in geological origin and in subtle but measurable ways. Celadonite forms in vesicular cavities and fractures of volcanic rocks and occurs as a relatively pure substance in small quantities; the most famous historical deposits were near Verona (Monte Baldo, Brentonico) and on Cyprus. Glauconite forms in marine sedimentary deposits and is more widely distributed but less concentrated.

Recent studies (Fanost et al. 2020) have shown that many commercial green earth pigments sold today do not contain celadonite or glauconite at all, but consist instead of gypsum, calcite, and organic dyes, making them unreliable in fresco painting and less stable in other techniques.

When burnt over a slow fire with gradually increasing heat, green earth converts to a fine warm brown, known as terra verde bruciata (burnt green earth). Italian painters used it, mixed with umber and other colors, for the shadows of flesh. Lomazzo directs that shadow color for flesh should be made with burnt green earth and umber; the Paduan Manuscript lists terra verde arsa among the colors for shadows of flesh, alongside umber and asphaltum.

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