# Prospecting Quartz Ore based on Specific Gravity



## Sunwell (Feb 19, 2022)

I have recently started hard rock prospecting in hopes of starting a hobby hard rock mine. I’m no professional and am learning as I go so there will be obvious holes in my question so please feel free to share any education as it will be appreciated and helpful. 

I’ve recently prospected a seem of quartz with a specific gravity of 3.28, I’ve come to a dead end with this method in understanding a worthwhile SG.

Pure quartz has a SG of 2.73, impurities range it from 2.71-2.75 the rock was 977~ grams with a volume of 298 mL. We’d expect 814~ grams at a SG of 2.73 which is 163~ grams difference. I’m hoping to crush and dissolve the rock in sulfuric or hydrochloric acid and see what’s left over before furthering refinement with aqua regia. 

Love any feedback around my methodology.


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## shrewdly (Apr 3, 2022)

Sunwell said:


> I have recently started hard rock prospecting in hopes of starting a hobby hard rock mine. I’m no professional and am learning as I go so there will be obvious holes in my question so please feel free to share any education as it will be appreciated and helpful.
> 
> I’ve recently prospected a seem of quartz with a specific gravity of 3.28, I’ve come to a dead end with this method in understanding a worthwhile SG.
> 
> ...


Specific gravity (SG) determinations are useful in mining applications, but have very little benefit in prospecting for ores. Ores being defined as any concentration of mineral(s) that can be extracted at a profit. A specific gravity determination that indicates a significant increase in the SG of the quartz sample does not tell you what is the source of the increase. Galena a common lead ore mineral has a SG of 7.4-7.8 a small quantity Galena could significantly raise the SG of your sample.
Barite (BaSO4) (SG 4.3 - 4.6) is commonly found in quartz veins, this too could raise the SG of your sample. Galena is a valuable mineral, Barite is not. 

If you are serious about prospecting I suggest you get a good mineral identification book so you can identify any minerals you may find. To help you recognize ore minerals in the field you should spend some time prospecting old abandoned mine sites. In particular the waste dumps, as there would be a variety of minerals in small sized pieces that would easier handle. 

Another thing is that if you want to start a hobby mine, abandoned mine waste dumps may provide an easy to process source of ore material. In particular mines from the 1890's to about 1920's are good targets as these were mined before modern techniques for mining lower grade ores were developed. A lot of these mines the ore was hand sorted prior to shipment and unless the rock had a high amount of ore mineral in it, the rock was simply discarded.

Local, State/Provincial, and Federal geological surveys have data bases and maps that are invaluable resources and their geologists are always happy to answer any questions you may have.
Local chamber of mines and prospecting associations are also another source of help and advice.


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## Alondro (Apr 3, 2022)

With quartz seams, one important mineral clue are rusty, weathered pyrites where ever moisture has had time to react. Gold can frequently be hiding in such pyrites. If you find bright specks in small pits where the pyrites have weathered out more or less completely, that might be native gold already. Powder and pan out a sample of anything like that.


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## Rick & Carrie (Apr 3, 2022)

shrewdly said:


> Specific gravity (SG) determinations are useful in mining applications, but have very little benefit in prospecting for ores. Ores being defined as any concentration of mineral(s) that can be extracted at a profit. A specific gravity determination that indicates a significant increase in the SG of the quartz sample does not tell you what is the source of the increase. Galena a common lead ore mineral has a SG of 7.4-7.8 a small quantity Galena could significantly raise the SG of your sample.
> Barite (BaSO4) (SG 4.3 - 4.6) is commonly found in quartz veins, this too could raise the SG of your sample. Galena is a valuable mineral, Barite is not.
> 
> If you are serious about prospecting I suggest you get a good mineral identification book so you can identify any minerals you may find. To help you recognize ore minerals in the field you should spend some time prospecting old abandoned mine sites. In particular the waste dumps, as there would be a variety of minerals in small sized pieces that would easier handle.
> ...


Post some photos and we will see what we can do for identifying any visible mineral content.


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## Rick & Carrie (Apr 3, 2022)

shrewdly said:


> Galena is a valuable mineral, Barite is not.


I disagree. 
Barite is an industrial mineral with many uses.

The main two uses are heavy drill mud in the petroleum industry, and to create radiation proof concrete, as Barium reflects radiation. As such it also has uses in the medical industry.


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## jobinyt (Apr 3, 2022)

I'm curious about why that particular seam of quartz attracted your attention. Secondly, trying to identify the constituants of something based on SG is a waste of time. Suppose there is 14 ounce of gold in 1 ton of your quartz. Not gonna happen but imagine - roughly $28,000 gold per ton. Let's see, 14 ounces gold equals 1 pound out of 2000 pounds of quartz - that's .05% based on weight - well inside the greater than 1% SG range you give for quartz. Third, almost anything interesting in quartz will separate after crushing and panning. You don't need to do a great job; just need to collect enough to use to analyze. AR is not the way to start. Once you know what it is, you can turn your attention to deciding if it is economically interesting and get a proper assay.

Oh, as Rick implies there are many industrial minerals of little value per ounce but given a large deposit could make you very rich. There many more such deposits in industrial minerals in the world than gold deposits.


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## shrewdly (Apr 4, 2022)

You are quite correct in stating that Baryte is a valuable mineral with many uses. Living in Alberta I have been known to toss (haha) a few bags of baryte around. I was using this in the context of what a hobby miner would encounter, in that scenario I won't find Baryte as a valuable mineral as it generally requires a highly mechanized mining system capable of moving large tonnages of material.


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## Rick & Carrie (Apr 4, 2022)

shrewdly said:


> You are quite correct in stating that Baryte is a valuable mineral with many uses. Living in Alberta I have been known to toss (haha) a few bags of baryte around. I was using this in the context of what a hobby miner would encounter, in that scenario I won't find Baryte as a valuable mineral as it generally requires a highly mechanized mining system capable of moving large tonnages of material.


A segregation crack 4 inches or more wide and infilled with Barite would meet prudent man rule by my standards.

Especially if seam sections showing mineral crystal structure were possible to be harvested. 

Such specimens can be sold on the mineral specimen market. 

We currently are preparing to do similar work with the four Anglesite filled stockwork vein systems we have found close to where we live. 

Two of which are in decomposed Greenstone.
Easy working material, but highly unstable for adit work.


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## jobinyt (Apr 4, 2022)

It appears OP has left the building.


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## jobinyt (Apr 4, 2022)

Dunno - never saw a big operation - just little guy with fewer big boy toys than a summer placer miner. It's an interesting world - the variation - how little some experience travels - yet how universal other experience. Not always sure of what I know and what I don't know - but GREAT fun.


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## shrewdly (Apr 5, 2022)

Rick & Carrie said:


> A segregation crack 4 inches or more wide and infilled with Barite would meet prudent man rule by my standards.
> 
> Especially if seam sections showing mineral crystal structure were possible to be harvested.
> 
> ...


I wish you well with your endeavours. If you some good pieces I would love to see some pictures.


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## Rick & Carrie (Apr 6, 2022)

shrewdly said:


> I wish you well with your endeavours. If you some good pieces I would love to see some pictures.


Shall do.
We have a few shelf specimens we collected a couple years ago that we can take photos of and post.


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## Rick & Carrie (Apr 6, 2022)

shrewdly said:


> I wish you well with your endeavours. If you some good pieces I would love to see some pictures.



The bright sunlight made good photos difficult.

I'll take some better photos after the sun goes behind the ridge.


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## Rick & Carrie (Apr 6, 2022)




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## snowdog20 (Apr 11, 2022)

Sunwell said:


> I have recently started hard rock prospecting in hopes of starting a hobby hard rock mine. I’m no professional and am learning as I go so there will be obvious holes in my question so please feel free to share any education as it will be appreciated and helpful.
> 
> I’ve recently prospected a seem of quartz with a specific gravity of 3.28, I’ve come to a dead end with this method in understanding a worthwhile SG.
> 
> ...


I've been doing it. With good success actually. PM we'll chat if you want...


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## jobinyt (Apr 12, 2022)

snowdog20 said:


> I've been doing it. With good success actually. PM we'll chat if you want...


What does good success mean?


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## snowdog20 (Apr 12, 2022)

jobinyt said:


> What does good success mean?


Check my other threads on forum. Graduated cylinder testing is the method you need to adopt, which enables precise cc measurements. The periodic table was created for a reason. Practice the method to identify Silver minerals, especially the big daddy Acanthite. It's very common, and generally near big gold also, or already with it.


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## snowdog20 (Apr 12, 2022)

Rick & Carrie said:


> View attachment 49390
> View attachment 49391
> View attachment 49392
> View attachment 49393
> ...


Don't use flash for silver pics, under natural/white light. Retake them.


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## Rick & Carrie (Apr 12, 2022)

There is


snowdog20 said:


> Don't use flash for silver pics, under natural/white light. Retake them.



There isn't any native element visible that would glare from reflective surfaces, so what would be the optical difference?

The bright sun seemed to be an issue, but the later set with the sun behind the ridge look pretty good. That being the case, what is your issue with the photos uploaded?


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## jobinyt (Apr 13, 2022)

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?


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## Rick & Carrie (Apr 13, 2022)

jobinyt said:


> 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?


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## orvi (Apr 13, 2022)

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.


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## jobinyt (Apr 14, 2022)

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


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## Rick & Carrie (Apr 14, 2022)

jobinyt said:


> 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.


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## goldshark (Apr 14, 2022)

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,


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## Rick & Carrie (Apr 15, 2022)

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.


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## shrewdly (Apr 17, 2022)

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


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## Rick & Carrie (Apr 17, 2022)

shrewdly said:


> 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.


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## shrewdly (Apr 24, 2022)

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


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## Rick & Carrie (Apr 24, 2022)

shrewdly said:


> 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.


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