Naked Science Forum

General Science => General Science => Topic started by: katieHaylor on 04/07/2018 16:43:04

Title: How do you calculate how much gold is in a rock specimen?
Post by: katieHaylor on 04/07/2018 16:43:04

Mark asks:

Is there a mathematical formula for working out the amount of gold in a rock specimen?

What do you think?

Title: Re: How do you calculate how much gold is in a rock specimen?
Post by: Bored chemist on 04/07/2018 17:12:47

Not really. You need to measure it in some way.

Title: Re: How do you calculate how much gold is in a rock specimen?
Post by: evan_au on 04/07/2018 23:17:14

Measuring the gold concentration often requires crushing the ore, and extracting the gold using toxic chemicals like cyanide and mercury.

Presumably, you could also use less-destructive effects like measuring X-Ray or gamma-ray absorption in the rock, compared to a rock sample with no gold. This could be complicated if the rock also has other heavy elements like Silver, Selenium or other Telluride minerals.

But the concentration of gold is very low, even in rich ores: perhaps 5 grams of gold in each ton of rock.

So to a first approximation, you could say that the rock in your hand is 0% gold.

See: https://en.wikipedia.org/wiki/Gold_extraction

Title: Re: How do you calculate how much gold is in a rock specimen?
Post by: Bored chemist on 04/07/2018 23:18:59

You could try this
https://en.wikipedia.org/wiki/Metallurgical_assay#Fire_assay/cupellation