  A search has been carried out for Magnetized Quark Nuggets (MQNs)
accumulating in iron ore over geologic time. MQNs, which are theoretically
consistent with the Standard Models of Physics and of Cosmology, have been
suggested as dark-matter candidates. Indirect evidence of MQNs has been
previously inferred from observations of magnetars and of non-meteorite impact
craters. It is shown in this paper that MQNs can accumulate in taconite (iron
ore) and be transferred into ferromagnetic rod-mill liners during processing of
the ore. When the liners are recycled to make fresh steel, they are heated to
higher than the Curie temperature so that their ferromagnetic properties are
destroyed. The MQNs would then be released and fall into the ferromagnetic
furnace bottom where they would be trapped. Three such furnace bottoms have
been magnetically scanned to search for the magnetic anomalies consistent with
trapped MQNs. The observed magnetic anomalies are equivalent to an accumulation
rate of ~1 kg of MQNs per 1.2 x $10^8$ kg of taconite ore processed. The
results are consistent with MQNs but there could be other, unknown
explanations. We propose an experiment and calculations to definitively test
the MQN hypothesis for dark matter.
