Pigments through the Ages - Technical Information

About the chemical structure:

Chemical name:	basic copper(II) carbonate
Formula:	2 CuCO₃.Cu(OH)₂
Crystal system:	Monoclinic - Prismatic (at Mineralogy Database)
Refractive index:	alpha =1.655, beta = 1.875, gamma = 1.909

Color:

Color Index (C.I.)

PG 39

How can you identify Malachite?

Imaging:

UVF: no

IRFC: blue

Analytics:

It's identified by means of FTIR and Raman. XRF can identify copper.

Raman spectra: University College London;

FTIR spectra: IRUG;

Usage and handling:

Permanence:	Toxicity:
lightfast: excellent Degradation processes: malachite has often proved to be permanent in oil paintings, although it may acquire a dull, brownish hue owing to the darkening of the oil. It is unaffected by exposure to light. In theory copper carbonate is blackened by sulfur compounds, so it may be affected by exposure to hydrogen sulfide found in polluted air. It is said to be incompatible with sulfide pigments, such as cadmium yellow, orpiment, realgar ultramarine, and vermilion. Even though theoretically subject to blackening when mixed with sulfide pigments, in practice this has never been reported. In tempera paintings, according to A. H. Church [Chemistry of Paints and Painting, p. 200] it is found to have stood well. Malachite passages on Italian frescoes are often still bright green.	moderately toxic. Malachite is moderately toxic and care should be used in handling the dry powder pigment to avoid inhaling the dust. MSDS: Natural pigments

Permanence:

Toxicity:

lightfast: excellent

Degradation processes: malachite has often proved to be permanent in oil paintings, although it may acquire a dull, brownish hue owing to the darkening of the oil. It is unaffected by exposure to light. In theory copper carbonate is blackened by sulfur compounds, so it may be affected by exposure to hydrogen sulfide found in polluted air. It is said to be incompatible with sulfide pigments, such as cadmium yellow, orpiment, realgar ultramarine, and vermilion. Even though theoretically subject to blackening when mixed with sulfide pigments, in practice this has never been reported. In tempera paintings, according to A. H. Church [Chemistry of Paints and Painting, p. 200] it is found to have stood well. Malachite passages on Italian frescoes are often still bright green.

moderately toxic. Malachite is moderately toxic and care should be used in handling the dry powder pigment to avoid inhaling the dust.

MSDS: Natural pigments