Brainspore:
One of the guiding principles behind the clock design was that they limited themselves to using materials humans have already worked with for at least 10,000 years so they could predict with confidence how such materials will hold up over a similar period of time. For example we know how a bronze object is likely to hold up over that period of time because we have artifacts from the Bronze Age, but we can only make educated guesses about what effect that period of time would have on steel and concrete.
Makes sense, but I’m reading through the website right now and it mentions use of 316 Stainless Steel, titanium and concrete being used in the clock design:
The Mechanism
The Clock is entirely mechanical, made of long-lasting materials, including titanium, ceramics, quartz, sapphire, and 316 stainless steel.
