Use Wear:
Ground Stones - Quartzite
Use-Wear Under Varied Lighting
A microscopic image will reveal use-wear and depending on the lighting, the absence of wear. Using directed light, natural light, or lighting the surface at an angle can result in different interpretations because the lighting can affect which features of use-wear are visible (Semenov 1964:23). I have been able to document how varied lighting contributes to analyzing use-wear.
Figure 1 was taken with the internal Dinolite microscope light turned off. Using natural light only, the reflected light (white specks in the image) provided better definition of the asperity tip fractures. The fractures are an indication that abrasive and/or fatigue wear, which contributes to the breaking off the tips of the asperities, can occur on a non-use surface possibly caused during deposition, extraction, or even lab storage and handling. This is important because it can be assumed that these types of tip asperity fractures are only caused through cultural practices, when in fact there may be other causes not related to normal use.
The implications of type of lighting used is seen in the additional examples provided. This wedimadqos surface observed with direct light (Figure 2) appears to be uniform in topographic levels, with some raised areas. However, by removing the direct lighting, and using only the natural light, Figure 3 reveals the topographic differences brought out through the shadows. The interstices are clearly observable.
Microscopic images taken from the unused (broken end) surface of SN 0704 Ona Adi madit from the Late Aksumite with varied lighting creates very different views. Figure 4 appears as a coarse textured surface, with an indication of an interstice on the right (circled). The depth of the interstice does not become evident until you remove the light in Figure 5. In this second image the individual fractured crystals also become more visible. These images confirm that it is imperative that surfaces be examined using different lighting to allow for the features to fully become visible during the investigative process of analysis.
For references cited related to this project, please click here.