A friend excitedly calls and tells you she found a hefty metallic yellow nodule in a nearby stream that weighs

Question

A friend excitedly calls and tells you she found a hefty metallic yellow nodule in a nearby stream that weighs 8.7 ounces! Now, you know there are other minerals besides gold that fit that description, but only gold has a specific gravity of 19.3. ‘Quick,’ you ask ‘what is its volume?’ By dropping the nugget into a graduated cylinder half filled with water she reports that the nugget’s volume is 12.757 cm3. Is your friend rich, or has she gotten excited over nothing? Use whatever calculations you think necessary to come to your conclusion and show your work. You may find the following conversions very useful:

1 gram (gm) = 0.035 ounces (oz)
1 oz = 28.3 gm

Answer 1

Well, given your conversions, and knowing that precious metals are priced in Troy ounces, not the more common Avoirdupois ounces (1 troy oz = 1.09714 Av. oz.) ...

The nodule has a mass of 246.21 grams, and displaced 12.757 grams of water. Therefore, its specific gravity is 246.21 / 12.757, or 19.299

She's right to get excited. The nodule is almost pure gold. With today's closing market price of $711.40 / troy oz. the nugget, weighing 7.9 troy oz., is worth about $5600. Not enough to make her "rich," per se. But still a pretty good day.