Prospecting Quartz Ore based on Specific Gravity

[Rick & Carrie]

I'm still mystified. Yes, the specific gravity of an homogenous sample of ore - eg acanthite or galena - can help identify that you have an ore. Wht I fail to understand is that you identify gold bearing quartz based on specific gravity.

Every summer I gather hundreds of pounds of silver bearing galena - most of it high grade but sometimes just highly modified host rock - very heavy stuff - easy to identify - just heft it in hand. But how might I use specific gravity to identify higher silver content pieces and how can I use specific gravity to identify gold bearing quartz - especially vuggy and 'dirty' quartz that seem quite likely to have a LOWER specific gravity than a piece of pure quartz, even if rich gold values are present. Are you able to identify non-free milling gold ore using specific gravity?

I guess it doesn't matter who says it or how it is stated.

Specific gravity can not be used to identify ores of specific metals.

There are way to many elements with similar specific gravity/heft to do that.

If the ore has a high heft, do some testing and or get an assay.

To nay say this is to be a moron.

Are you a moron?

 

[orvi]

With specific gravity determined mass % of certain mineral/element, heavy assumptions are made. Firstly, you assume that there are no cracks or cavities inside the rock. Second, you assume that there is nothing else present than your target metal and host rock of known density.

It is fairly uncommon that you find just gold in quartz. Most of the times, there are also sulfides (also heavy, and in higher percentage than gold), there could be iron oxides, barite, etc... And it is not possible to calculate it precisely, if you do not have at least the ratio between say gold and pyrite. Mathematically impossible to do.

I don´t know, it must be a big big rich specimen to calculate gold content based on gravity. At least few % to get some reliability into the numbers. For just regular ore rocks, I wouldn´t do this.

 

[jobinyt]

Most of us are on exactly the same page - it is snowdog20 that I was hoping to clarify, eg, his basis for saying SG testing is giving good results in searching for silver. The two don't go together, but that tells us only that one is wrong, not which one is wrong

 

[Rick & Carrie]

Most of us are on exactly the same page - it is snowdog20 that I was hoping to clarify, eg, his basis for saying SG testing is giving good results in searching for silver. The two don't go together, but that tells us only that one is wrong, not which one is wrong

Agreed. When it comes to mineralized rock as possible ore; if it has high heft, bench test to identify what elements it contains, or a broad spectrum analysis, then get an assay.

 

[goldshark]

Lets look at the effects of say 36 oz. per ton gold ore. This would be approximately 3 lbs. Troy extra weight to a ton that weighs 1997 lbs. ( I am doing approximations ,as I have had a couple good Margs, and don't need the brain damage of exact math). This relative additional specific gravity will raise the overall specific gravity from say 2.7 to 2.72. Not enough to be able to make a good concentrate separation. What I do is look for particles with a higher concentration of gold to quartz ratio ( via placer concentrates in my case) in maybe the 5 sg. range. This is worth going after. What I am saying is that to take a general ore of say 2.8 s.g, and try to enrich it based solely on specific gravity, will not work. There are too many heavy minerals which could be included, based on strictly s.g.. Unless you have picture rock material, which you could easily hand sort, I do not understand how you could guesstimate what is good ore. Since fine crushing/ grinding is required, then you can increase your s.g. per particle, optimum size unknown, and increase the quantities of valuable components then. I hope this explains what the process is,

 

[Rick & Carrie]

Crush the ore, produce a concentrate, then leach and electrowin the leach solution, or smelt the concentrate with an appropriate flux to produce a dore button which can then be chemically refined with the methods here on this forum.

 

[shrewdly]

Rick and Carrie: Thanks for the photos. They're nice specimens and it appears you have a good source for them.

 

[Rick & Carrie]

Rick and Carrie: Thanks for the photos. They're nice specimens and it appears you have a good source for them.

Thanks, and you're welcome.
We will post assay results soon.

We are living in swarm zone. Four stockwork systems and three stringer veins. All within a quarter mile of where we live.

The better sections showing crystal structure we will sell as shelf specimens.

Some of the lesser fragments will be used as part of our ore identification kits.

The rest will be crushed and processed to recover the lead and silver.

 

[shrewdly]

We are living in swarm zone. Four stockwork systems and three stringer veins. All within a quarter mile of where we live.
You sound like you're living on the edge of an old caldera.
As to Lead recovery. A learned couple told me to "Beware of Zinc." Ha Ha

 

[Rick & Carrie]

We are living in swarm zone. Four stockwork systems and three stringer veins. All within a quarter mile of where we live.
You sound like you're living on the edge of an old caldera.
As to Lead recovery. A learned couple told me to "Beware of Zinc." Ha Ha

There were many volcanic vent systems here in the Oregon Cascades.

Zinc enriched bedrock is abundant here.

 

[The 420 Kid]

With specific gravity determined mass % of certain mineral/element, heavy assumptions are made. Firstly, you assume that there are no cracks or cavities inside the rock. Second, you assume that there is nothing else present than your target metal and host rock of known density.

It is fairly uncommon that you find just gold in quartz. Most of the times, there are also sulfides (also heavy, and in higher percentage than gold), there could be iron oxides, barite, etc... And it is not possible to calculate it precisely, if you do not have at least the ratio between say gold and pyrite. Mathematically impossible to do.

I don´t know, it must be a big big rich specimen to calculate gold content based on gravity. At least few % to get some reliability into the numbers. For just regular ore rocks, I wouldn´t do this.

I'm confused I thought that as long as you took the driveway and divided it by 1.9 and took the wet weight and likewise divided it by 3.1 and then took the equal of both of those numbers and subtracted them from each other it would give you a rough estimate of how much gold is in your ore regardless of total composition.

 

[Martijn]

I'm confused I thought that as long as you took the driveway and divided it by 1.9 and took the wet weight and likewise divided it by 3.1 and then took the equal of both of those numbers and subtracted them from each other it would give you a rough estimate of how much gold is in your ore regardless of total composition.

driveway = dry weight?

that's not what I meant to say sorry I got to stop using talk to text when I do this.

Please do so
where did you get the 1.9 from?

 

[Yggdrasil]

I'm confused I thought that as long as you took the driveway and divided it by 1.9 and took the wet weight and likewise divided it by 3.1 and then took the equal of both of those numbers and subtracted them from each other it would give you a rough estimate of how much gold is in your ore regardless of total composition.

The amount of Gold in an ore do not contribute with a measurable amount to the SG.
The host mineral is what you are calculating and that can say if it is or not what you think it is.

 

[The 420 Kid]

The amount of Gold in an ore do not contribute with a measurable amount to the SG.
The host mineral is what you are calculating and that can say if it is or not what you think it is.

Thank you for the clarification. Can you please post the mathematical formula?

 

[The 420 Kid]

Thank you for the clarification. Can you please post the mathematical formula?

In asking that I do realize that all wars would be a different SG however you can substitute or for a letter to encompass where it would go regardless of what type of work would be in the equation. Please and thank you.

 

[Yggdrasil]

In asking that I do realize that all wars would be a different SG however you can substitute or for a letter to encompass where it would go regardless of what type of work would be in the equation. Please and thank you.

Please rephrase it do not make sense, at least not to me!

 

[Yggdrasil]

Thank you for the clarification. Can you please post the mathematical formula?

The mathematical formula is simply weight divided by volume.

Mass/Volume
for Gold it is 19.3 grams per ml ie SG 19.3
for water it is 1 g per ml equals SG 1