Crossing the Borders: New Methods and Techniques in the Study of Archaeological Materials from the Caribbean

Investigating Stone Bead Drilling Techniques / 83
slurry in the drill hole, particularly in the initial phase of drilling. Drilling was
undertaken in half- hour stages. During these 30 minutes, the wooden drill would
have to be replaced between 6 to 10 times due to attrition. If the drill bit were too
long, it would snap immediately if too much pressure was applied to it. After about
30 minutes the sand particles from the drilling slurry became wedged into the bottom
of the borehole and were difficult to remove. It was necessary to remove the
compacted slurry, however, before further drilling progress could be made. To ease
both molding and examination of the experimentally produced drilled materials,
these pieces were cut in half, exposing the drill bore. This allowed examination of
manufacturing traces on the actual bore surface as well as the mold.
Results
Figure 6.2 illustrates different images of the experimental piece (experimental calcite
#1) and its mold taken with a stereomicroscope and SEM. The images taken
with the stereomicroscope offer more realistic views of the item, due to the enhanced
depth of field. They also offer excellent views of the general shape and
macroscopic features of the borehole. In this case, the prominently conical shape
of the borehole is very obvious. If the bottom of the actual borehole is examined
(Figure 6.2a), it can be observed that the leading edge (arrow #1) is relatively flat.
There are prominent furrows (arrow #2 and arrow #3) near the leading edge that
give it a steplike appearance. The mold (Figure 6.2b), which offers a negative impression
of the object, is particularly effective in illustrating the shape of the larger
scale features such as a number of faint furrows (arrow #4), which are difficult
to image on the actual experimental piece. These furrows are concentric features,
but are less prominent than the ones closer to the leading edge, nor do they demonstrate
the polish of the leading edge furrows visible on the SEM image, as described
below.
SEM imaging is necessary in order to examine finer- scaled features. Two obvious
features that can be observed on the composite SEM image (Figure 6.2c) are
areas of localized and more generalized polish. The two prominent furrows giving
the leading edge its steplike appearance (arrow #2 and arrow #3) are represented on
the SEM images as linear polished bands extending around the borehole. Similar
bands of polish are not in evidence in locations farther up on the borehole where
the less prominent furrow features were observed on the mold (Figure 6.2b, arrow
#4). There is also a prominent area of polish on one side of the borehole outlined
by the oval in Figure 6.2c. Many of the other features and textures visible on the
SEM image are that of the calcite itself, including a large fracture.
We were fortunate to have an archaeological example of a partially drilled calcite
bead to compare with our experimental piece. Again, the mold imaged with
the light microscope provides an excellent view of the overall shape of the bore
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