According to Arthur C Binning, Pennsylvania Iron Manufacture in the Eighteenth
Century, p139, American pig iron was marked as a result of the 1750 Act of
Parliament (Journals of the House of Commons, XXV, p. 979 & 115; and 23 George
II, c. 29, Sections 1,2,7).  The only problem being that most of the Virginia
pig iron I  have seen is pre 1750.

Swedish pig was also marked.  This is discussed in  the 1918, more recent
facsimile, Patrik Möller, "Svenska järnstämplar : sammanställd efter Kungl.
Patent- och registreringsverkets upplaga från 1918", Gamleby : Arkeoförl.1987,
133+44 pages).  And also in Dahlgren, Erik Wilhelm, "Järnvräkeri och
järnstämpling: ett bidrag till den svenska järnhandelns historia", Stockholm :
Jernkontoret 1930, Jernkontorets bergshistoriska skriftserie ; [1], 343 pages).

Has anyone read the Swedish works? I do not read Swedish.

JH Brothers IV