Crystal Skulls Deemed Fake
L'articolo illustra una varietà di sitemi scientifici atti a dimostrare oltre ogni dubbio che i teschi di cristallo aztechi altro non sono che falsi. E' giusto che la Scienza si difenda: qualsiasi ne sia il motivo (economico, ideologico, altro) si tratta sempre di una frode.
A potpourri of analytical techniques reveals purported Aztec sculptures are not bona fide
By
Humans seem to have a predilection for fake quartz-crystal
Aztec skulls. Since the 1860s, dozens of skull sculptures have appeared
on the art market purporting to be pre-Columbian artifacts from
Mesoamerica, that is, created by the indigenous peoples of Mexico and
Central America prior to Spanish exploration and conquest in the 16th
century. Three such skulls have graced the collections of major museums
on both sides of the Atlantic: the Smithsonian Institution in
Washington, D.C., the British Museum in London, and the Quai Branly
Museum in Paris.
As early as the 1930s, some experts began to have doubts about the authenticity of the skulls, says Margaret Sax,
a conservation scientist at the British Museum. But for a long time
researchers “didn’t have the scientific means to follow up” on their
hunches, she adds. Over the past two decades researchers at all three
museums have capitalized on analytical science innovations to show that
these peculiar skulls are not unusual Aztec artifacts but post-Columbian
fakes.
Nowadays the market for crystal skulls is limited to Indiana Jones
fans, New Age devotees, and people in the goth and punk subcultures. But
in the 1860s, when the skulls appeared on the market, many people in
Europe sported little skeletons on rings, pendants, or other personal
trinkets to remind them of their own mortality, says Jane Walsh,
an archaeologist at the Smithsonian’s National Museum of Natural
History. It was a French dealer named Eugène Boban who capitalized on
this fascination with the macabre, as well as Europe’s growing interest
in and ignorance of Mesoamerican artifacts, to slip some of the first
sham skulls into museums.
Walsh has traced fake crystal skulls at the British Museum and the Quai Branly Museum
back to Boban, who sold them to art dealers who then sold them to the
museums more than 100 years ago. The Smithsonian skull, however, showed
up in the mail in 1992, as an anonymous donation. Its arrival motivated
Walsh to contact the British Museum to discuss the skulls. That
conversation catalyzed the scientific and historical research that
finally proved the objects were phonies.
The British and American team were particularly suspicious of the
skulls because they hadn’t come from documented archaeological sites.
And something was wrong with the skulls’ teeth. Although skulls do
appear as motifs in Aztec art, most representations of teeth in
authentic pieces reflect the dentistry—or lack thereof—of the time. The
teeth in the suspect skulls seemed too linear, too perfect, Sax
explains.
So the team took a closer look at the skulls’ surfaces. As a
benchmark, they borrowed a legitimate Mesoamerican crystal goblet from
the Museum of Oaxacan Cultures, in Mexico. Then they used scanning
electron microscopy to compare these surfaces.
It turns out that the surface of the authentic goblet has irregular
etch marks, a sign that the pieces were carved with hand-held tools. But
the surface of the suspect skulls have regular etch marks, evidence
that they were made with rotary wheels and hard abrasives, which
appeared only after the Spanish conquest of Mexico, Walsh says.
Looking even closer at the British Museum’s skull, the team
discovered green, wormlike inclusions in the rock. Raman spectroscopy
revealed that the inclusions were an iron-rich chlorite mineral.
Although this kind of trace impurity is found in rock crystal from
Brazil or Madagascar, it is not found in Mexican crystal, Walsh says.
The team also noticed a small deposit of something curious in the
Smithsonian’s skull. By using X-ray diffraction they discovered the
deposit was silicon carbide, a synthetic abrasive used in stone-carving
workshops only starting in the mid-20th century. This damning residue
revealed the Smithsonian skull had likely been made mere decades before
the anonymous donor sent the skull by mail, Walsh says.
As the British Museum and Smithsonian researchers began amassing
evidence in the 1990s and 2000s that the skulls in their collections
were certainly not of Aztec origin, museum staff at the Quai Branly
Museum decided to scrutinize a crystal skull and a human head sculpture
in their collection. Both objects were acquired through the
controversial dealer Boban, and both were purported to be pre-Columbian.
The crystal skull at the Quai Branly Museum, like the fakes at
the Smithsonian and British Museum, had a suspiciously perfect set of
teeth, whereas the head had more realistic human features, the French
researchers noted in a 2009 report (Appl. Phys. A, DOI: 10.1007/s00339-008-5018-9).
The French team dated the two objects using a noninvasive method that
measures how deep water penetrates into rock objects. The method relies
on shooting helium ions at an object’s surface and analyzing the
interaction of the ion beam with the hydrogen in water at increasing
depths in the sculpture. Then the water penetration is compared with
samples of known ages. They found that the crystal skull had likely been
made after the Spanish conquest, whereas the anthropomorphic head was
likely made in pre-Columbian times.
The fact that one of the Boban-sourced artifacts at the Quai Branly
Museum is fake whereas the other is probably a legitimate pre-Columbian
artifact speaks to the dealer’s fascinating and controversial role in
the movement of Mesoamerican artifacts in the late-19th century. Boban
initially left France to join California’s gold rush, but after failing
to strike it rich, he went to Central America and began exporting Mayan
and Aztec artifacts, says Walsh, who is writing a book about him. “Most
of the objects he sold were legitimate,” she says. “But his big-ticket
items were for the most part fake.” A century after his crimes, modern
analytical chemistry continues to help museum researchers separate
Boban’s bona fide pieces from the bogus.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © 2013 American Chemical Society
