Etruscan jewelry
The combination of metals was a basic technique. Essentially, there is no such thing as 24 carat gold jewelry. Massive gold is the most malleable metal. It is almost like wax. In order to have jewelry that can pass the test of time and gravity, the Etruscans had to combine their gold with other metals.
Mu-metal
Mu-metal typically has relative permeability values of 80,000–100,000 compared to several thousand for ordinary steel. It is a "soft" ferromagnetic material; it has low magnetic anisotropy and magnetostriction, giving it a low coercivity so that it saturates at low magnetic fields. This gives it low hysteresis losses when used in AC magnetic circuits. Other high-permeability nickel–iron alloys such as permalloy have similar magnetic properties; mu-metal's advantage is that it is more ductile, malleable and workable, allowing it to be easily formed into the thin sheets needed for magnetic shields.