According to this site :http://chestofbooks.com/crafts/mechanics/Workshop-Receipts-3/Iron-Alloys.html
Gold produces toughness, and a yellow colour; this alloy is used for small iron castings. It doesn't give a percent of alloy though.
3 parts iron and 1 of gold enter into fusion together at a temperature inferior to that necessary for melting iron; equal parts of the 2 metals give, by fusion, a greyish mass, somewhat brittle, and attracted by the magnet; with 6 parts gold and 1 of iron, a white alloy is obtained, which is attracted by the magnet, ductile while cold, and at a moderate heat becomes yellow, red, and blue; 9 of iron and 1 of gold form an alloy which resists the file, unless previously subjected to a red heat; with 28 of iron and 8 of gold, the alloy is as white as pure silver, and more yielding under the fire and hammer than ductile' iron. According to Hatchett, the alloy formed with 11 parts gold and 1 of iron is very ductile, of great resisting power, and harder than gold. Without any preparation, it can readily be cut into blocks, laminated, or struck into medals. This alloy is of a pale yellowish-grey colour, approaching dirty white.
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Allow me to provide a disclaimer that I am not knowledgeable in anything concerning this matter except google, so I cannot vouch for the accuracy.