German, Sternmarke, Ruhrort, Phosphate Seal, Image & Found by Peter van Lierop.
Found in Gemert, Netherlands, 15mm, 3.6g.
WERK / RUHRORT curved up // five-pointed star
See Euro Plombs, "Sealed leads for agricultural phosphates from the "Thomas" process which is a historic pig iron refining process derived from the Bessemer converter. It bears the name of its inventors who patented it in 1877: Sidney Gilchrist Thomas and his cousin Percy Carlyle Gilchrist. Here the phosphates come from the 'Werk Ruhrot-Meiderich' foundries. The star on the obverse is the registered trademark for "Thomas" phosphates. Seal from the period between the two world wars. ... Ruhrort."