It could be pure gold gilt off of some object, and if so, it could be 300 years old or more. Could have been from one of those old wrecks and been floating around in the sea for years. Old
PURE gold like that fools people into thinking it was something lost yesterday. I would recommend you have it tested for purity.
Keep these things in mind & maybe the light test that is mentioned here might indicate something.
Gold Leaf: Averages 0.1 microns. If you hold it up to a light source, it is so thin that it becomes semi-transparent.
Gold gilding is incredibly thin. Standard gold leaf (used for gilding) averages about 0.1 to 0.12 microns in thickness. This means it is significantly thinner than regular paper—which is usually around 100 microns thick—and is even thinner than a strand of human hair. [
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One troy ounce (approx. 31.1 grams) of pure gold can be stretched into a continuous, unbroken wire or thread up to
50 miles (80 kilometers) long.
This extreme length is due to gold's unrivaled
ductility, which is its physical property allowing it to be drawn out into a thin wire without breaking. At this length, the resulting thread is incredibly microscopic, measuring roughly 5 micrometers (or 5 microns) in diameter.