Natural Science in Archaeology

218 9 Pigments and Colorants
Maya Blue. Maya Blue is a bluish-green pigment that has been found associated
with Mayan artifacts in Central America. Its use appears to have extended into the Colonial
Period (Tagle et al. 1990). Maya Blue is a mixture of minerals and indigo – a blue
dye obtained from various plants. The mineral constituents are palygorskite (formerly
called attapulgite) and sepiolite (also called meerschaum). The pigment is notable not
only for its association with specific archaeological contexts, but also for its unique
physical properties. Maya Blue is known to have survived the extremely harsh environmental
conditions of the rain forest. It is also remarkably resistant to alkalis and all but
hot concentrated acids (Gettens and Stout 1966).
Maya Blue appears to have had special cultural significance for the Maya beyond
its decorative qualities. According to the sixteenth century bishop and explorer
Diego de Landa, the Maya painted their victims before sacrificing them on a stone
altar. Maya Blue was employed extensively on ceremonial objects and temple
murals (Arnold and Bohor 1975).
There has been considerable debate regarding the precise nature of Maya Blue.
Most scientists now agree that this pigment has a substantial clay component. However,
there is no consensus regarding the source of the pigment’s blue color. There
are two theories regarding the source of color in Maya Blue. Some scientists have
suggested that Maya Blue is a lake consisting of an indigo-stained attapulgite clay.
However, the marked stability of Maya Blue is inconsistent with the notorious instability
of modern manufactured lakes, and, until recently, there was some question
regarding the availability of attapulgite clay to the Maya (Arnold and Bohor 1975).
However, possible sources of attapulgite have now been identified in Guatemala
and the northern Yucatan Peninsula (Folan 1969).
Research has been conducted regarding the possible effects of heat processing as
a possible explanation for the apparent stability of Maya Blue. It has been suggested
that heating indigo-stained attapulgite at moderate temperatures for several days
will result in a relatively stable compound (Van Olphen 1966; Littmann 1982).
An alternative theory regarding the color source in Maya Blue is that the pigment
derives its color from iron. This possibility was presented early in the Maya Blue
debate by Gettens and Stout (1966). However, this theory has been disregarded
because of the low concentrations of metallic impurities found in Maya Blue. Nevertheless,
some scientists have continued to explore the possible role of metal compounds
in Maya Blue (Jose-Yacaman et al. 1996).
Lapis Lazuli/Natural Ultramarine. Although lapis lazuli, the mineral lazurite,
also known as ultramarine, (Na,Ca) 8 (AlSiO 4 ) 6 (SO 4 ,S,Cl) 2 , was available to the
ancient Egyptians, there is no evidence that it was used as a blue pigment until much
later. Lapis was expensive, and its application as a pigment required processing by
levigation of the powdered material. The resulting yield would have been very low,
making lapis far too expensive to utilize in this manner (Lucas 1989).
The earliest known use of natural ultramarine as a paint pigment is found in wall
paintings at the cave temples of Bamiyan in Afghanistan (sixth to seventh century
CE). Ultramarine is also known from Chinese paintings of the tenth to eleventh
centuries and from Indian murals as early as the eleventh century. In Europe, ultramarine
found favor in illuminated manuscripts of the fourteenth to mid-fifteenth