From the article: My emphasis.
Conclusion
A functional analysis of the drilling of a granite sarcophagus lid from the Old Kingdom period has begun to suggest resolutions to an important scholarly controversy between Petrie and Lucas, and has produced some preliminary insights into the hitherto speculative technology used. These are: 1) loose, dry abrasives (except diamond) did not produce concentric lines; 2) fixed abrasives or those in a watery slurry or a lubricant such as olive oil did produce concentric cutting lines; 3) corundum and diamond cannot be ruled out as not having been used to drill granite. These findings are significant in the history of ancient lapidary technology and will be useful in research on other stones. The discovery of the significance of the concentric lines, and also their significance as an indicator of the abrasive employed, will be useful for further research. Each type of stone will have to be dealt with separately.
Why are you unable to accept the fact that ancient peoples had some remarkable technological skills?
