Germanium

Germanium is the most scarce element of the carbon group.
But it may be the most useful in advanced mechanosynthesis with …

• its tetra-valency and
• its bindnig strength that is neither to high as (as with carbon) or to low (as with lead or perhaps tin)

For advanced mechanosynthesis germanium is needed only in extremely low trace amounts. So low abundance is a non issue here.

See: tooltip chemistry & tooltip preparation zone