Study of two large crystal skulls in the collections of the British Museum and the Smithsonian Institution

British Museum skull

The life-size carving of a human skull in the British Museum collection was made from a single block of rock crystal (a clear colourless variety of quartz). According to Museum records, the skull was acquired in 1897 from Tiffany and Co., New York, through Mr George Frederick Kunz. In one of his numerous publications, Kunz states that the skull was brought from Mexico by a Spanish Officer before the French occupation. It was sold to an English collector and acquired at his death by Eugène Boban, a French antiquities dealer, later becoming the property of Tiffany and Co.

Human skulls and skull imagery were known to have featured in Aztec art and iconography in Mexico at the time of first contact with the Spanish in AD 1519. They were worked by Aztec, Mixtec and even Mayan lapidaries, and a human skull covered with turquoise and lignite mosaic is displayed in the Mexican gallery (Room 27) of the British Museum. However, they were usually carved in relief in basalt or limestone as architectural elements.

The authenticity of skulls made of quartz crystal soon came to be questioned. Although some are said to be examples of colonial Mexican art for use in churches, perhaps as bases for crucifixes, they may be among the large quantities of forgeries produced during the second half of the nineteenth century, when interest in collecting ancient artefacts from Mexico was at its height in both the United States and Europe. 

Some of these pieces made their way into museum and private collections. Scientists at the British Museum examined the British Museum skull several times between 1950 and 1990. Observations made with a binocular microscope suggested that the techniques of carving were probably atypical of pre-Columbian times. Also, the large piece of rock crystal used for the skull was thought to have come from Brazil, an area far outside the ancient trade network of Mexico.

Smithsonian skull

An increasing number of large and small quartz skulls have become known, particularly in recent decades. None has ever been reported from well-documented official archaeological excavations. In 1992, almost a century after the crystal skull was acquired by the British Museum, a particularly large white (or milky) quartz skull with a hollow cranium was sent anonymously to the Smithsonian Institution, Washington D.C. An accompanying note said the object was bought in Mexico City in 1960. The carving, like the British Museum skull, is stylistically somewhat anomalous when compared with ancient Mesoamerican depictions.  For example on both skulls, the rigid linearity of features representing teeth contrasts with the more precise execution of teeth on pre-Columbian artefacts. The arrival of the white quartz skull led to a study of archival documents concerned with the early history and acquisition of several crystal skulls in museum collections. It became apparent that not only had the dealer, Eugène Boban, owned the British Museum skull (as alluded to above), he had previously also been involved in the sale of three other rock crystal skulls, one around 11 cm high and two small ones (less than 5 cm high), currently in the Musée du Quai Branly, Paris.

Collaborative study

In 1996, a collaborative programme of authenticity studies was set up between the British Museum, the Smithsonian Institution and also the Department of Earth Sciences and Geography at Kingston University, London. Small skulls carved from rock crystal have perhaps attracted less public attention than larger examples, and the investigations were focused on the origin of the large skulls in the two national museums. Because stone objects cannot be dated satisfactorily by the techniques available today, the aim of the project was to answer three questions. How were the skulls carved?  Where did the large pieces of quartz originate from?  What is known about the early history of the skulls?

The approach developed during the 1990s in the British Museum for investigating carving methods was adopted for the study of skulls. This usually enables the use of tools and techniques to be identified from the fine detail of the carved features or ‘tool marks’ preserved on hard stone objects. In the investigation of the skulls, the faint tool marks remaining on the highly polished surface of the British Museum skull and the pitted matt surface of the Smithsonian skull were examined under a microscope and in a scanning electron microscope. They were compared to the tool marks remaining on several rock crystal objects from well-documented excavations in Mexico City and Oaxaca, Mexico. The regular characteristics seen on both skulls showed they were mainly worked with rotary wheels in conjunction with very hard abrasives. The characteristics contrasted with those seen on pre-Columbian carvings, which were carved with hand-held tools.

The white quartz material of the Smithsonian skull is of relatively common occurrence, but the large clear quartz crystal used for the British Museum skull would have been obtained from a special source. Because the characteristics of inclusions in clear quartz may indicate the geological conditions under which the original crystal formed, the mineral composition and the fine detail of the inclusions in the clear crystal of the British Museum skull were investigated. These ongoing investigations are providing information on the provenance of the source.

To address the history of the British Museum skull, further archival research is underway. When complete the information that is being obtained will be combined with the results of the examination of the skulls, enabling detailed descriptions to be made of the origins of these two large carvings, which will form the core of a joint publication.

More information about this research

G.F. Kunz, Gems and Precious Stones of North America. New York, pp. 285-286, 1890.

C. McEwan, A.P. Middleton, C. Cartwright and R. Stacey, Turquoise Mosaics from Mexico.  London, British Museum Press, 2006.

M Jones, “The Limits of Expertise”, in: Fake? The Art of Deception. London, British Museum Publications, pp. 296-297, 1990.

J.M. Walsh, “Crystal skulls and other problems”, in: Exhibiting Dilemmas: Issues of Representation at the Smithsonian, A. Henderson and A.L. Kaeppler (eds.). Washington and London, Smithsonian Institution Press, pp. 116-139, 1997.

J.M. Walsh, “Falsificando la historia, los falsos objetos prehispánicos”, Archaeologia Mexicana Vol XIV(82), 2006.

J.M. Walsh, “Legends of the crystal skull. Why Indiana Jones might want to rethink his latest quest”, Archaeology Magazine, in press.

M. Sax, N.D. Meeks, and D. Collon., “The introduction of the lapidary engraving wheel in Mesopotamia”, Antiquity 74(284), pp. 380-387, 2000.

A.H. Rankin, “Fluid inclusions; a new look at ancient fluids in crystals”. Geology Today Vol 5, pp. 21-24, 1989.

A.H. Rankin, “Fluid inclusions – tools for geological investigations”, in: Encyclopaedia of Geology, R.C Selley, R. Cocks and I. Plimer (eds.). Elsevier Science, Chapter 9, pp. 253-260, 2005.