An alloy of gold made with nickel. Sometimes the jeweler also mixes palladium or zinc in the alloy. White gold has a brighter and whiter color than silver due to the nickel content.
Widmanstatten lines
Etching slices of meteorites with nitric acid allow patterns known as "Widmanstatten lines" to be more visible. These lines and patterns are the result of the meteorite cooling in outer space over billions of years.