AbstractShepard has described several principal types of temper used in pre-Hispanic ceramics in northern Yucatan. One of these, identified as “volcanic ash,” has long been a mineralogical problem because no unequivocal deposits of volcanic materials are known to exist in the area.The possible indigenous materials that could have been identified as “volcanic ash” have been examined and the conclusion reached that the material in question is the mineral palygorskite. This mineral is widespread in the peninsula and is often associated with the mineral sepiolite. Palygorskite (also known as “attapulgite”) was known to the Maya as sak lu'um (white earth) and has been identified by high temperature studies as a constituent of Mayan ceramicware. Its origin, in Yucatan, is attributed to direct precipitation in shallow marine waters and in hypersaline, fringing lagoons. It is suggested that, unless ceramicware from Yucatan is found that actually contains true volcanic detritus (glass shards, grains of feldspar, amphibole, pyroxene, rutile, zircon, and so forth), reference to “ash temper” be avoided.
The influence of crystallinity on high–temperature syn–eruptive gas uptake by volcanic ash
