Specific Gravity Specimen Test for Gold Content

Just wondering if someone could help me work out an approximate gold content in a specimen.
It is ironstone with lets say 20% quartz with gold showing freely from most sides.
Its weight is 25.1 grams dry and 20.3 grams suspended in water which gives a difference of 4.8 grams.
I worked out 14.62 grams gold if it was only quartz but not even sure if I worked that out correct.
I would expect the gold content to be less due to the heaver ironstone and it would be appreciated if someone who has some knowledge in working these things out could tell me how or let what the gold content should be.
It's not going to the dolly pot as it's too nice and will be for collection only and no I wasn't the lucky one to find it.
Regards Mark

Hello Mark,
Try this.
http://www.gold-nuggets.org/specific-gravity-test.htm

Congrats on your nugget.
See you up them thar hills.
Frank

Hi Mark,
the most difficult thing with SG tests is the specific gravity (or relative density) of the host rock. For every 1% you get it wrong, you will be 1% less accurate. Quartz varies a lot in density from 2.6-3 and iron oxide varies even more, 3.3-4.5. A mixture of both is a nightmare . Often, a visual estimate or one with a high frequency VLF detector
will give you a reasonable idea of gold content. Best method is the dolly pot !
But, I have a copy of the excellent 'stab in the dark' method devised by the late Chris Hake. When I see you next, I'll give you copy. This relies less on accurate host SG and is surprisingly reliable. Cheers, Dwt

does that work on large gold painted rocks PW??

Thanks Frank and DWT.
I had a look at the site and have a better idea now and also thanks DWT I will take you up on that offer.
Regards mark

Hi Mark,
no worries, will run off a copy for you. Steve, ya cheeky bugger No, it wasn't 'gold painted rocks', it was gold painted lead! A friggin huge slab of it...thats why it convinced so many people! Plus the fact the rumour and photos were being spread by some serious 'heavy hitters' in the Triangle. These guys find over a hundred ounces each year, easy...and have found plenty of big lumps too. An analogy is like Kevin Rudd telling everyone that the Indonesians have invaded the Northern Territory (and showing photos). Just how many people would believe that on day one???? EVERYONE! There are still a few stubborn people who reckon the 300+ ouncer was real, even today! Cheers, Dwt

Old thread re-kindled, hope this doesn't give anyone nightmares

Is there a limit on size that these conversions work? surely a formula works for any size....

I recieved an email today saying that this person has a quartz speci, weighs dry 0.91 & wet 0.20 They told me that they came up with a negative gold content...I laughed and said ya can't have a negative gold content, until I did some conversions and then I was laughing at myself aswell.....any idea's guys.

I know that some of you are doing this all of the time so would appreciate some thoughts or even better, an answer.

Cheers

"weighs dry 0.91 & wet 0.20"

0.91g - 0.20g = 0.71g this will be the actual wet weight

Dry weight 0.91x1.9 = 1.729
Wet weight 0.71x3.1 = 2.207
2.207 - 1.729 = 0.478 grams of gold

Remember that to get the wet weight you can either place a beam across the scale and hang the specie in the water, this gets the answer you want, if you place the water on the scale and hang the specir into it yu then need to minus the dry weight from this number to get the wet weight.

Also make sure that there are no air bubbles stuck in or on the specie as this will also give a lighter wet weight.

cheers dave

Here is some more useful info.

http://www.nqminersden.com/specific.htm

And this one

http://www.gold-nuggets.org/specific-gravity-test.htm

Yes, i was wondering where they come up with the 1.9 and 3.1 figures when working out specific gravity?

Thank you . deaselanding