Prospecting Quartz Ore based on Specific Gravity

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Sunwell

Member
Joined
Feb 19, 2022
Messages
7
Location
Oregon
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.
 
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.

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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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.
 
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.
 
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.

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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Post some photos and we will see what we can do for identifying any visible mineral content.
 
shrewdly said:
Galena is a valuable mineral, Barite is not.
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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.
 
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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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.
 
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.
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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.
 
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.
 
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.

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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I wish you well with your endeavours. If you some good pieces I would love to see some pictures.
 
shrewdly said:
I wish you well with your endeavours. If you some good pieces I would love to see some pictures.
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Shall do.
We have a few shelf specimens we collected a couple years ago that we can take photos of and post.
 
shrewdly said:
I wish you well with your endeavours. If you some good pieces I would love to see some pictures.
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The bright sunlight made good photos difficult.

I'll take some better photos after the sun goes behind the ridge.
20220406_162635.jpg20220406_162629.jpg20220406_162552.jpg20220406_162558.jpg20220406_162643.jpg20220406_162648.jpg20220406_162613.jpg20220406_162623.jpg
 
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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.

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.
Click to expand...
I've been doing it. With good success actually. PM we'll chat if you want...
 
jobinyt said:
What does good success mean?
Click to expand...
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.
 
There is
snowdog20 said:
Don't use flash for silver pics, under natural/white light. Retake them.
Click to expand...

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?
 
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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