17th Century Frame – Decorative Stones

Frame (originally a portable altar?)
Rome, first half of the 17th century, ebony with pietre dure decoration, 61 x 35 x 10 cm, double-sided painting attributed to Pieter Aertsen (1508-1575), Christ Bearing the Cross (front) and the Annunciation (reverse), oil on panel, The Samuel Courtauld Trust, The Courtauld Gallery, London, P.1978.PG.3

This richly decorated frame was probably designed in the 17th century as a portable altar for use in a private chapel. It is beautifully inlaid in pietre dure with a multitude of semi-precious stones. All the stones are the product of a geological process called mineralization, which is the infiltration and percolation of fluids into cavities in rocks.

Lapis lazuli is a rock, a natural aggregate of one of more minerals, that has been mined in Afghanistan since antiquity. It owes its deep blue colour to the presence of the mineral lazurite in its chemical composition. The highest grade of lapis lazuli was traditionally selected for use in decorative inlays and also ground up into the pigment, ultramarine, for painting.

Amethyst and agate are both composed of the mineral quartz. They were commonly found in Bohemia and the Black Forest during this period and were traded in the renowned stone-cutting workshops of Idar-Oberstein in Germany.

Although now depleted, Sicilian jaspers (diaspri di Sicilia in Italian) were mainly found in the province of Palermo and were highly admired for their wide variety of colours and patterns – hundreds of types are known. These variations arise from the existence of impurities in their chemical composition.


Rocks and Minerals

A rock is a natural composition of one or more minerals. A mineral is a naturally occurring, inorganic solid with a defined chemical composition and an ordered atomic structure.

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Decorative Stone Identification

Identifying decorative stones, such as those used in the Courtauld Gallery’s pietre dure frame, may be one of those instances where scientific investigation is actually inappropriate.

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Lapis Lazuli

Originating from the Persian word lazhuward meaning ‘blue’, and the Arabic word lazaward meaning ‘sky’, lapis lazuli is a rock composed primarily of the minerals lazurite, pyrite and calcite.

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Amethyst is a purple variety of quartz. Its regal colouring appears in a range of hues, varying from light lilac to deep indigo depending on the abundance of iron in its chemical composition.

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Agate is a variety of quartz characterised by its concentrically banded appearance. Banded agate forms by the permeation and build-up of layers of silica in cavities within rocks.

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Sicilian Jasper

Referred to as diaspri di Sicilia in Italian, Sicilian jaspers are very hard and occur in a multitude of colour and pattern variations, making them ideal stones for decorating ornaments.

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Pietre Dure Decoration

This frame is characteristic of the richly decorated portable altars of the Baroque period, which were commissioned by wealthy individuals for their private chapels, and that was likely its original function.

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I would like to thank Dr Ruth Siddall, Senior Lecturer in Earth Sciences at UCL, and Monica Price,  Collections Manager at the Oxford University Museum of Natural History, for their invaluable expertise in decorative stone identification, continued guidance and their generosity for lending us rock and mineral samples from their collections for the display. 
I also wish to thank the following scholars for their time and knowledgeable insight: Professor Aviva Burnstock, Professor and Head of the Department of Conservation and Technology at The Courtauld Institute of Art; Silvia Amato, PhD student and Technical Assistant at The Courtauld Institute of Art; Graeme Barraclough, Chief Conservator at The Courtauld Gallery; Matthew Thompson, gallery technician at The Courtauld Gallery; Dr Emma Passmore, Senior Teaching fellow in Earth Sciences at Imperial College London; Nadine Gabriel, MSci Geology student at UCL; the furniture historian, Simon Jervis, as well as the frame historian, Lynn Roberts.


Bonewitz, R. (2008). Rocks & Minerals: The Definitive Visual Guide. 2nd ed. London: Dorling Kindersley Limited.

Cennini, C. and Thompson, D. (1960). The craftsman's handbook: "Il Libro dell'Arte" Cennino d'Andrea Cennini. 1st ed. New York, N.Y: Dover.
González-Palacios, A. (2010). Concerning Furniture: Roman Documents and Inventories. Furniture History, 46, pp.1-135.
Koeppe, W. and Wardropper, I. (2008). Art of of the Royal Court: Treasures in Pietre Dure from the Palaces of Europe. 1st ed. New York: Metropolitan Museum of Art.
Pabian, R., Jackson, B., Tandy, P. and Cromartie, J. (2006). Agates: Treasures of the Earth. 1st ed. London: Natural History Museum.
Price, M. (2007). Decorative stone. 1st ed. London: Thames & Hudson. Price, M. and Cooke, L. (n.d.). Corsi Collection of Decorative Stones. Available at: http://www.oum.ox.ac.uk/corsi/
Swynfen Jervis, S. (2006). 'Review of Arredi e Ornamenti alla Corte di Roma by Alvar González-Palacios. The Burlington Magazine, 149, pp.422-23.