Fig. 5.

Microphotographs of combustion by-products observed in Riwi thin sections (reproduced from Vannieuwenhuyse 2016). a Burnt bone displaying brownish colour (R515B, PPL, scale 100 μm); b inflorescence fragment charred by heat of combustion features and microcharcoals mixed in geogenic sediments (F14-A, thin section R502B, PPL, scale 500 μm); c, d charcoal fragments and ash particles, note the ash calcitic crystal (bright) high interference colours (F6-B, R507C, PPL and XPL, scale 1000 μm); e non-disturbed ashes showing colour variation from yellowish to grey and the presence of phytoliths in the outer parts (F2-C, R509A, PPL, scales 500 and 1000 μm); f articulated ash particles with typical prismatic shape at high magnification (F2-C, R508B, XPL, scale 100 μm)