  There have been many searches for magnetic monopoles in flight, but few for
monopoles in matter. We have searched for magnetic monopoles in meteorites,
schists, ferromanganese nodules, iron ores and other materials. The detector
was a superconducting induction coil connected to a SQUID (Superconducting
Quantum Interference Device) with a room temperature bore 15 cm in diameter. We
tested a total of more than 331 kg of material including 112 kg of meteorites.
We found no monopole and conclude the overall monopole/nucleon ratio in the
samples is $<1.2 \times 10^{-29}$ with a 90\% confidence level.

High Energy Physics - Experiment