This flint blade from Denmark was made by the indirect percussion technique.  The blade dates to the end of the Mesolithic period, during the Ertebølle phase, ca. 6100-7500 BP.  This was prior to the introduction of agriculture into the region in the Funnel Beaker (Neolithic) period, ca. 6000 BP.

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Patches of silica gloss are visible on the edges of this blade, although the gloss is not visible in the 3D model.  Gloss on flint blades is common on flint tools from Mesolithic Europe.  Silica gloss is found on a variety of stone tools in prehistory, most notably on tools used to harvest grains, but also on hoes and digging tools, cylindrical adzes for processing sago palm, and a variety of stone flakes used in cutting tasks.  Stone flakes with silica gloss date to the Late Pleistocene period in Indonesia and persist into the relatively recent past.  The formation of these gloss patches is not completely understood, but the gloss patches appear to be a ‘crust’ rich in carbonates that accrue on the tool during use, combined with mechanical damage and silica replacement of certain minerals in the crust from lying in the soil for thousands of years.

Ertebølle blades with gloss patches largely disappear from sites by ca. 5500 BP, during the Neolithic period, when something about the shift to agriculture makes the tools obsolete.  The timing of their disappearance suggests that it must be related to a change in subsistence, and that the silica gloss was associated with a food source that became less important as reliance on domesticated cereal crops increased.  Analysis of the gloss patches, combined with replications studies, suggest that they were used to cut and process fresh silica-rich reeds to make objects used in fishing activities in wetlands (e.g., fish traps or baskets), and when wetland fishing declined with the advent of agriculture, edge-gloss on blades eventually disappeared.

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People during the Ertebølle phase were strongly oriented to the Baltic Sea and North Sea around Denmark and southwestern Sweden, practicing a mixed hunting-gathering-fishing economy.  Their long-term living sites—referred to as ‘kitchen middens’—are rich with shells, fish and terrestrial animal bones, and tools made from flint, bone, and antler.  High-quality flint is abundant in this region, and Ertebølle flintknappers were skilled practitioners of the indirect percussion blade-making technique.

Indirect percussion involves placing a punch on the platform edge of the core and detaching the blades by striking the end of the punch.  By using a punch, the flintknapper can precisely manipulate the placement and angle of the blow that initiates fracture.  Punches made from curved tines of red deer antlers were found at an Ertebølle phase site called ‘Grube-Rosenhof LA 58’, located in northern Germany.