high-grade ore

We just don't have enough cheap, high-grade ores of almost any kind.

Gamma radiation may also be a hazard to those working close to high-grade ores.

This was in part due to the exhaustion of supergene (shallow) high-grade ores.

The lawyers may squabble over the details, but a few billion dollars worth of high-grade ores will start a feeding frenzy among the brokers.

Japan’s post-war reconstruction, which was based on developing heavy industry, saw a country with no raw materials import high-grade ores from the nearest source—Australia.

High-grade ores always needed.

While high-grade ores have now been exhausted, lower-grade taconite continues to supply a large proportion of the nation's needs.

High-grade ores found in Athabasca Basin deposits in Saskatchewan, Canada can contain up to 23% uranium oxides on average.

By the mid-sixteenth century, it was well known in Spain that American silver production was in decline due to the depletion of high-grade ores and increasing production costs.

In ensuring years, high-grade ores became harder to find and harder to get to and more work was done on the processing of tailings for the low-grade ores it contained.