  A search for stable strange quark nuggets has been conducted in helium and
argon using a high sensitivity mass spectrometer. The search was guided by a
mass formula for strange quark nuggets which suggested that stable strange
helium might exist at a mass around 65 u. The chemical similarity of such
``strangelets'' to noble gas atoms and the gravitational unboundedness of
normal helium result in a large enhancement in the sensitivity of such a
search. An abundance limit of no more than $2 \cdot 10^{-11}$ strangelets per
normal nucleus is imposed by our search over a mass region from 42 to 82 u,
with much more stringent limits at most (non-integer) masses.
