Illuminating Objects: Borrowing specimens from the Oxford University Museum of Natural History

Illuminating Objects intern Natasha Gertler tells us about her research.

The art of identifying decorative stones, such as those in the Courtauld’s Baroque frame, is achieved through observation, connoisseurship and comparison with other stones of known identity, rather than scientific analysis. Composed of exactly 1000 polished stone slabs of uniform shape and size, the extensive Corsi collection was established in Rome in the first quarter of the 19th century and is now housed in the Oxford University Museum of Natural History. Most of the stones are of known provenance and hence the collection is an excellent resource for decorative stone identification.

As soon as we were introduced to the collection, we immediately contacted Monica Price, the author of the comprehensive Corsi collection website as well as the Head of Earth Collections at the Oxford University Museum of Natural History. She kindly agreed to visit the Courtauld to view the frame and her extensive knowledge of decorative stones proved to be invaluable.

What was previously thought to be a wine-coloured variety of jasper, Monica identified to be in fact most likely an inlay of the mineral amethyst backed with a red metallic foil. This became very apparent when the segment was illuminated and viewed through a microscope, producing a reddish orange glow through the translucent purple amethyst, as shown below.

Amethyst probably backed with red metallic foil

Amethyst probably backed with red metallic foil, illuminated and viewed through a microscope

From a very early stage of my Illuminating Objects internship, I decided to display the frame alongside specimens of rocks and minerals that correspond to the stones present in the frame. I wanted to do so in order to emphasise the beautiful results of the interplay of man and nature, by highlighting the stones’ transformations from rough to cut and polished, revealing the true beauty of nature’s wonders.

Having already accumulated samples of lapis lazuli and amethyst from private collections in London, Monica kindly offered to lend us a variety of Sicilian jaspers and agates from the Earth Collection of the Oxford University Museum of Natural History. Sicilian jaspers are now depleted and no longer quarried, so it is very fortunate to be able to include a selection in my display.

Enthusiastically accepting her generous invitation, I readily booked my train ticket and off to Oxford I went. The stone slabs of the Corsi collection are splendidly preserved in drawers away from public display, and remain in Corsi’s original arrangement. His arrangement is very significant as he was one of the few collectors of his time who attempted to order their collection according to the geological properties of the stones rather than superficially by aesthetic similarities.

The Corsi collection is magnificent. Almost bursting in awe, I perused the stones, locating brilliant samples of my favourite rocks and minerals whilst discovering new colours and patterns I thought only to be imaginable.

I could have continued for hours but work had to be done. Monica kindly showed me the agates and Sicilian jaspers from the Earth Collection that I could choose to borrow. Having made my selection with Monica’s helpful guidance, and filled out the necessary paperwork, I returned back to the Courtauld Gallery with the specimens under my fierce protection. Glowing with joy, I now had everything I needed for the display.

The Oxford University Museum of Natural History

The Corsi Collection

Natasha Gertler and Monica Price with the Corsi collection

Stone slabs of Sicilian jaspers from the Corsi collection, corresponding to those present in the Courtauld frame