Source material, pottery

Earlier it was stated that provenance determination is inherently more complex for pottery than for obsidian. In general, pottery itself rather than clay is used as source material to establish the composition of pottery that was made locally. 

Pottery as source material has some assets, one of which is the ancient potters knowledge of which clays in an area were (and are) best for pottery making. If we were to search for these clays, we would be faced with a tedious, and largely blind, sampling. In addition, it is often unpractical or even impossible to mount clay-collection expeditious to distant places in which one is interested. 

The drawback in using pottery as source material lies in the necessity of making a strong case that the pottery was indeed made locally. This... 

Material from the Gezer excavations had already been obtained. The geologist provided a sample of limestone clay local to Gezer, which however was from a deposit that had not been exposed in antiquity. Previous studies (8) have shown that the pottery at Gezer was made from the two main types of clay sources. 

ICP spectroscopy has been applied in quantitative elemental analysis in forensic examinations (57), and for such issues as the determination of source provenance based on these data for materials such as ochre (58) or other pigments. Speakman et al. (59) report on the characterization of archaeological materials with LA-ICP-MS, while others analyzed pigments successfully on pottery from the American Southwest (60), including the Mesa Verde region (61) among others. 

Home is the most important setting for infants and young children. They often eat, play, and sleep in the same area. Examples of sources of exposure to pollutants include building materials (e.g. wood treated with arsenic-based pesticides), lead-based paints, insecticides that are sprayed indoors, fuel (e.g. coal and wood) for indoor cooking, disposal practices for domestic waste (e.g. incineration), household chemicals (e.g. solvents), and small-scale enterprises at the family residence (e.g. brick producers who operate low-technology combustion kilns and makers of pottery using lead-based paints). 

Within the northern Valley of Guatemala whiteware tradition, there is a basic dichotomy between Sacojito-Chinautla whiteware and Durazno whiteware. Durazno potters exploit sources of whiteware clay different from the source used by Sacojito-Chinautla potters (55). Durazno whiteware pottery and raw materials therefore should be distinguishable from Chinau-tla-Sacojito whiteware. 

Of course, once the ore is obtained from its deposit, the actual work of extracting the desired metal has yet to be accomplished. In addition to metals, a variety of other substances comprise natural minerals. Since aluminum and silicon are the most prevalent elements in the Earth s crust, most of the metals exist naturally as aluminates, silicates, or aluminosilicates. The most common minerals are feldspars and clays. These materials have been used since ancient times for the production of materials such as pottery, brick, and china. An example of a feldspar is K2Al2Si60i6, which corresponds to a mixture of potassium superoxide, alumina, and silica (K20-Al203 6Si02). Upon contact with water and carbon dioxide, a weathering reaction results in kaolinite, an aluminosilicate clay (Eq. 1). However, in addition to these oxidized sources of metals, there are substances such as alkaline carbonates, sulfates, phosphates, as well as organic matter that need to be removed to yield the desired metal. As you would expect, the yield for this process is quite low ores typically possess less than 1 % of the desired metal ... 

In order to understand chemically analyze the materials found at archaeological sites it is essential to understand something about their context - sources, technology, use, and disposal. In this chapter, we examine some of the more common raw materials at archaeological sites - rock, pottery, bone, sediments, metals, and other things like shell, pigments, charcoal, and plant remains (Fig. 3.1). There aie many other materials, generally less common, that we do not consider here. 

The most basic level of analysis, identification of ceramic material, is readily made in the field. The next level of analysis, the raw materials that were used, is usually done to ascertain the geographic source of the pottery. This usually includes morphological and stylistic information that assigns the ceramic to a culture area... 

Shellfish belong to the biological group of species known as mollusks, animals with a shell and a foot. Univalve mollusks have one shell and include many species of snails, conchs, and others. Bivalve mollusks have two shells and include clams, scallops, and oysters. There are many species of mollusks and both freshwater and salt water varieties. In addition to their use as food, shells were often used to make beads, fishhooks and other objects. Crushed shells have been used as a source of lime, for pottery temper, and as construction material. In some areas such as the South Pacific, shells of species like the cowrie have been traded as valued items over long distances and even used as money. 

Strontium isotopes, reported as the ratio Sr/ Sr, have been used primarily in the study of human movement in the past. There are, however, a number of other potential applications usually involving the sourcing or proveniencing of other kinds of objects and materials such as pottery, stone, textiles, or animals. 

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