Developing an understanding of the process of sickle sheen formation is critical in evaluating archaeological interpretations of such deposits, or their absence, on flaked stone tools. A series of controlled experiments was carried out to evaluate extant hypotheses of plant silica depositions on stone tools. The results of experimentation were documented with the scanning electron microscope. Based on the documentation, several conclusions were reached:
(1) two distinct types of sickle sheen are produced from the processing of plant materials;
(2) the type of sickle sheen produced is dependent upon the stage in the life cycle of the plant when processed; and
(3) the different extant hypotheses for the processes and products of sickle sheen deposition could be a result of either differing preparation techniques or different research interests.
- https://www.jstor.org/stable/23272990?seq=1#page_scan_tab_co...

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Note added at 59 mins (2019-09-09 13:55:23 GMT)
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Sickle-gloss, or sickle sheen, is a silica residue found on blades such as sickles and scythes suggesting that they have been used to cut the silica-rich stems of cereals and forming an indirect proof for incipient agriculture - https://en.wikipedia.org/wiki/Sickle-gloss