A gyron is a single segment of a gyronny field. It is described in period heraldic tracts [e.g., Legh 68], but does not appear to have been used (at least with that blazon) in period armory. Hence, only the gyron found in the tracts – issuant from dexter chief as in the illustration – may be used in Society armory. For related charges, see pile.
Iohann se pipere bears: Sable, a gyron argent.
Martin de Montriere sur Mer bears: Azure, on a gyron argent a heart sable.