At Brazil's largest imperial topaz mine, the recovery is about how many pounds per 8,000 tons of ore?

• A. 660 pounds
• B. 6.6 pounds
• C. 132 pounds
• D. 66 pounds

Answer: (D)

Recovery tells you how much gem material you get back from processing a certain amount of ore. When the problem uses the phrase pounds per 8,000 tons, it’s giving a total yield for that block of ore. If the recovery is about 66 pounds for every 8,000 tons, it means you’d expect about 66 pounds of imperial topaz from 8,000 tons of ore. That works out to a per-ton yield of 66 divided by 8,000, which is 0.00825 pounds per ton. In grams, that’s roughly 3.75 g per ton—a small but real amount, which fits the idea of a modest recovery from bulk ore. The other numbers would imply much different yields per 8,000 tons, so they’re not consistent with the stated recovery.