herb
spending too much on rocks
Member since November 2011
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Post by herb on Aug 30, 2016 14:41:07 GMT -5
I have this mystery rock that I was hoping somebody could identify. It's specific gravity is around 8.38. It will scratch a penny (mohs 3 or 3.5 depending on where you look) A nail will scratch it. (mohs 5.5, I think) A magnet is not attracted to it. The raw surfaces (pics 1 and 2) have kind of a greenish tint to it, like the patina copper gets. The cut surface (pic 3) and the rubbed smooth area (pic 2) look like the color silver gets when it tarnishes. (Both the cut and the rubbed area are not fresh, they are years old) The area where I scratched with a nail is a bright silver color. The first picture shows the outer surface IMG_4801_zpswi8k2eqp by Shiny Objects, on Flickr] This picture shows the top. There is a spot that is rubbed smooth at the bottom edge IMG_4800_zpsomvujkmq by Shiny Objects, on Flickr Here is a cut surface. IMG_4804_zpsmht8qogn by Shiny Objects, on Flickr Another view of the cut surface. That line towards the bottom right is where the nail scratched it IMG_4802_zpsmq0nnhzx by Shiny Objects, on Flickr
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Post by greig on Aug 30, 2016 14:58:07 GMT -5
My best guess is nickeline (AKA niccolite) which is a nickel arsenide (nickel and arsenic) Good idea to wash your hands before eating. I find a lot of it with my metal detector outside of Cobalt, Ontario. When sliced, the metal is a kind of coppery colour (rather than bright silver). The stain on the outside of the rock is green. It can be associated with silver either in vein or as a mixed metal. Sometimes, the arsenic is replaced by antimony, which forms breithauptite (AKA nickel antimonide), but a slice of this is usually more of a grey-silver colour than I see in your picture.
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Deleted
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Post by Deleted on Aug 30, 2016 18:21:31 GMT -5
greig does your Nicoline take a high polish? If so, you have customers here. herb Great identify post. Scratch test and SG!! Woot!! Sadly, It's out of my league. Did you do a streak?
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herb
spending too much on rocks
Member since November 2011
Posts: 469
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Post by herb on Aug 31, 2016 8:03:56 GMT -5
My best guess is nickeline (AKA niccolite) which is a nickel arsenide (nickel and arsenic) Good idea to wash your hands before eating. I find a lot of it with my metal detector outside of Cobalt, Ontario. When sliced, the metal is a kind of coppery colour (rather than bright silver). The stain on the outside of the rock is green. It can be associated with silver either in vein or as a mixed metal. Sometimes, the arsenic is replaced by antimony, which forms breithauptite (AKA nickel antimonide), but a slice of this is usually more of a grey-silver colour than I see in your picture. Thanks for the info! Nickeline looks like a good match. Good thing I always wash my hands after handling rocks! Does it have any lapidary usefulness? Seems like it would make a nice cab to begin with, but not so much when it tarnishes.
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herb
spending too much on rocks
Member since November 2011
Posts: 469
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Post by herb on Aug 31, 2016 8:04:09 GMT -5
No, I kept my clothes on Seriously though, does one need anything special for a streak plate? Or will just the back of any ceramic tile work?
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Post by greig on Aug 31, 2016 9:12:38 GMT -5
No, I kept my clothes on Seriously though, does one need anything special for a streak plate? Or will just the back of any ceramic tile work? I use both black and white streak plates and they typically cost less than $5 CDN each, so my guess is you can get them for $2-$3 USD each from any rock shop or mineral show. If you want to use just a white one (most common), the back of a porcelain tile will work fine. All you are doing is scratching the rock onto something white to see the colour. I have heard people use the underside of the cover on the back of a toilet for this purpose. However, my fancy/schmancy toilets cost over $700 and my wife would kill me if I tried. LOL
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Post by greig on Aug 31, 2016 11:51:16 GMT -5
greig does your Nicoline take a high polish? If so, you have customers here. herb Great identify post. Scratch test and SG!! Woot!! Sadly, It's out of my league. Did you do a streak? So, hijacking the thread:
The metals that I find that I am calling Nickeline usually take a high polish and do not seem to oxidize very fast. The rocks with green stain/bloom on the outside (indication of nickel) have probably been in the ground (removed from the vein) for more than 100 years. The rocks of course vary in mineral content, usually by which mine and even which shaft they were from. It also depends which part of the actual vein.
A general way to see some of the rocks I am discussing is to look at my YouTube channel, search on my ID tess99991 and look at the playlist "Metal Detecting Native Silver".
FYI - The old timers in Cobalt Ontario were focused on silver and some of their early high grade was 4000oz silver/ton. Even later, most mines did not intentionally process anything less than 100 oz/ton. That is amazing because I have been to other mines in the province that were excited about 10 oz/ton silver.
I had a few rocks XRF assayed, that I identified by sight as nickeline - tested for the purpose of refining for silver and they typically contained less than 5% silver and the refiner therefore wanted minimum of 1000 lbs. The surprise was they also had trace amounts of PGM (Ruthenium, Palladium, Iridium and Platnum - about 1-2%) and even trace amounts of gold (about 0.5%). From the ones XRF tested, the nickel is usually more than half plus around 20% cobalt. However, classic nickeline is about 50:50 NiAs. My personal suspicion is the arsenic over time has mostly dissolved away. In fact, when freshly dug, some of these rocks and the surrounding soil have a thick green slime, which I suspect is mostly arsenic and I was able to wash most of it off (or really bad habit, rub it off on my pants).
These kind of metals in pure form or as a mixed metal ore typically shine up pretty good, but it of course will depend on the individual rock and its content. When I am metal detecting, I usually just field classify the stuff that gives a strong signal on the metal detector as nickel, cobalt, silver or breithauptite (NiSb). Unless I see obvious silver on the outside, I usually leave behind the cobalt or breithauptite (I should probably rethink that).
If I trust the results of the XRF, these ore samples that I call Nickelline are probably better identified as Langistite (Co,Ni)As or Sudburyite: (Pd,Ni)Sb or perhaps something else. I have also sometimes been (pleasantly) surprised many times by some rocks when cut or tumbled with their better silver content within.
So Shotgunner - bottom line after this long winded explanation, is I would be happy to sell/ship rocks to you (or others) and would love to see your results. I constantly play with these rocks too and like the idea of them going to someone that appreciates them. I have them in all shapes and sizes (from little 1/4 oz nuggets up to 80 lb monsters) and solid metal or rock with vein. If anybody else is near Toronto, PM me and you can inspect/choose what you want. Otherwise, give me an idea of what you want and I will take some pictures (ie size, quantity, slices, partially sliced or whole) and put a price on it.
Perhaps, what I probably should do is put together some pieces into couple of lots and post them in the sell section of this forum and see what happens.
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metalsmith
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Post by metalsmith on Aug 31, 2016 13:01:45 GMT -5
I'm happy to be informed otherwise but I thought As minerals were often yellow /orange. I do know that Ni in chrysoprase is responsible for the green colouration.
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Post by greig on Aug 31, 2016 14:30:49 GMT -5
I'm happy to be informed otherwise but I thought As minerals were often yellow /orange. I do know that Ni in chrysoprase is responsible for the green colouration. Good observations.
My comments were my own theory of what I see in the field and trying to explain the lower As within the ore. I believe As dissolves in water, but Ni does not and both oxidize over time in the presence of Oxygen. Furthermore, I suspect As and Ni oxidize from the rocks to create the green bloom or slime. Either the bloom is not yellow/orange because the green is an overwhelming colour (I don't believe this) or there is one more process at play (I think so). I believe the As washes away faster than the Ni, so Ni oxidation is left in higher abundance and therefore the bloom is green. Anyway in this video is me metal detecting in Apr2016 and you can see the slime on rocks at 48 seconds and 2:40:
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metalsmith
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Post by metalsmith on Aug 31, 2016 15:46:26 GMT -5
If you do think there's arsenic in there, best stop rubbing the stuff on your trousers: dermal absorption
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ziggy
spending too much on rocks
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Post by ziggy on Sept 7, 2016 21:47:33 GMT -5
I have this mystery rock that I was hoping somebody could identify. It's specific gravity is around 8.38. It will scratch a penny (mohs 3 or 3.5 depending on where you look) A nail will scratch it. (mohs 5.5, I think) A magnet is not attracted to it. The raw surfaces (pics 1 and 2) have kind of a greenish tint to it, like the patina copper gets. Nickeline only has a specific gravity of 7.8. It also has a hardness of 5 to 5.5 which would win the battle over the nail. Mohs Hardness of Common Objects fingernail 2 to 2.5 copper 3 nail 4 glass 5.5 knife blade 5 to 6.5 steel file 6.5 streak plate 6.5 to 7 quartz 7 My money goes on Algodonite Algodonite is a copper arsenide mineral with formula: Cu6As. It is a gray white metallic mineral crystallizing in the hexagonal system. It has a Mohs hardness of 4 and a specific gravity of 8.38 - 8.72. Not magnetic. The copper would help explain the greenish tint. Some uncut Algodonite is pictured below Second guess would be Domeykite Domeykite is a copper arsenide mineral, Cu3As. It crystallizes in the isometric system, although crystals are very rare. It typically forms as irregular masses or botryoidal forms. It is an opaque, white to gray (weathers brassy) metallic mineral with a Mohs hardness of 3 to 3.5 and a specific gravity of 7.2 to 8.1. Not magnetic. Below is some sliced Domeykite Last guess would be Mohawkite which is basically a mixture of Domeykite, Algodonite, and native copper. Streak: Brownish Specific gravity is between 7.2 and 7.9. Luster: Metallic Hardness: between 3 and 3.5. Not magnetic. All three of my candidates are copper arsenic mixtures so nothing changes in the handling department. Below is a pic of some cut Mohawkite Notice that all three of my choices are specific gravity of at least 7.9 with the S.G. 8.38 of Algodonite a dead ringer for your sample as well as the Mohs hardness of 4 which is also dead on. The fact that the hardness of the nail and the Algodonite are both 4 on the mohs scale is ok. A nail will scratch another nail. Seems to me that Nickeline has two strikes against it right off the bat considering the mismatch in stats. Nickeline has a specific gravity of only 7.8. It also has a hardness of 5 to 5.5 which would as previously stated would put up a good fight against the nail. All three of my choices can have inclusions of quartz, which looks like what I'm seeing in your slice.
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Deleted
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Post by Deleted on Sept 7, 2016 22:07:06 GMT -5
If its copper, sulfuruc acid will probably turn blue.
Sulfuric at home depot or lowes. I forget which. One sells lye and the other sulfuric acid. Cant explain why, but I keep both around here at Casa de Shotgunner.
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ziggy
spending too much on rocks
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Post by ziggy on Sept 7, 2016 22:23:05 GMT -5
If its copper, sulfuruc acid will probably turn blue. Sulfuric at home depot or lowes. I forget which. One sells lye and the other sulfuric acid. Cant explain why, but I keep both around here at Casa de Shotgunner. www.quora.com/Does-sulfuric-acid-react-with-copperCopper does not directly react with sulfuric acid so some form of oxidant is needed. Hydrogen peroxide and nitric acid are excellent oxidants and the first two methods demonstrate this. The nitric acid method however produces toxic nitrogen dioxide gas so you'll need to perform this one outside or in a fumehood. Also found on the same link Yes, if the acid is concentrated enough and mixture is heated. Copper turnings are dropped into a flask. Concentrated sulfuric acid is added to the copper in the flask. The mixture is heated. The heated air expands, and is pushed out of the flask. The copper reacts with the acid. One of the products is sulfur dioxide gas, which fills the flask. After the heat is removed, the gas in the flask cools, and contracts, drawing water into the flask. Initially, the water vaporizes due to residual heat, and expands rapidly. Again it cools, and water is drawn again into the flask. As water enters the flask, the sulfur dioxide gas evolved in the reaction dissolves. The pressure in the flask is reduced, which draws more water into the flask. When a concentrated solution of ammonia is added, the copper(II) ion in solution reacts to form a complex ion, which is blue in color. The previous paragraph explains the procedure needed to get blue color from copper and sulfuric acid. I think I'll skip the final step which is adding the concentrated solution of ammonia. Unfortunately, that's how you get the blue stuff to confirm its copper. I don't think the sulfuric sold at the local hardware store is concentrated enough either.
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ziggy
spending too much on rocks
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Post by ziggy on Sept 7, 2016 23:46:30 GMT -5
My question for you is what are the things I have circled in red? They look like native copper crystals or massive inclusions. The things in black circles? They look like quartz inclusions. The thing in yellow reminds me of things I've seen sticking out of copper ore. Is that thing a crystal too?
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Deleted
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Post by Deleted on Sept 7, 2016 23:56:07 GMT -5
If its copper, sulfuruc acid will probably turn blue. Sulfuric at home depot or lowes. I forget which. One sells lye and the other sulfuric acid. Cant explain why, but I keep both around here at Casa de Shotgunner. www.quora.com/Does-sulfuric-acid-react-with-copperCopper does not directly react with sulfuric acid so some form of oxidant is needed. Hydrogen peroxide and nitric acid are excellent oxidants and the first two methods demonstrate this. The nitric acid method however produces toxic nitrogen dioxide gas so you'll need to perform this one outside or in a fumehood. Also found on the same link Yes, if the acid is concentrated enough and mixture is heated. Copper turnings are dropped into a flask. Concentrated sulfuric acid is added to the copper in the flask. The mixture is heated. The heated air expands, and is pushed out of the flask. The copper reacts with the acid. One of the products is sulfur dioxide gas, which fills the flask. After the heat is removed, the gas in the flask cools, and contracts, drawing water into the flask. Initially, the water vaporizes due to residual heat, and expands rapidly. Again it cools, and water is drawn again into the flask. As water enters the flask, the sulfur dioxide gas evolved in the reaction dissolves. The pressure in the flask is reduced, which draws more water into the flask. When a concentrated solution of ammonia is added, the copper(II) ion in solution reacts to form a complex ion, which is blue in color. The previous paragraph explains the procedure needed to get blue color from copper and sulfuric acid. I think I'll skip the final step which is adding the concentrated solution of ammonia. Unfortunately, that's how you get the blue stuff to confirm its copper. I don't think the sulfuric sold at the local hardware store is concentrated enough either. I am thinking whomever wrote that has never tried it. None of the gas evolution happened nor was the heat required in my copper plating bath. The stuff from the hardware store is 3/4 strength if memory serves. Nonetheless, it doesn't address my suggestion that a drop of sulfuric probably reacts with copper arsenic compound to make a blue color. Did say probably. Not discussing production quantities. Just a tiny qualitative test. But, thanks for being safety police.
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ziggy
spending too much on rocks
Member since June 2016
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Post by ziggy on Sept 8, 2016 9:54:21 GMT -5
www.quora.com/Does-sulfuric-acid-react-with-copperCopper does not directly react with sulfuric acid so some form of oxidant is needed. Hydrogen peroxide and nitric acid are excellent oxidants and the first two methods demonstrate this. The nitric acid method however produces toxic nitrogen dioxide gas so you'll need to perform this one outside or in a fumehood. Also found on the same link Yes, if the acid is concentrated enough and mixture is heated. Copper turnings are dropped into a flask. Concentrated sulfuric acid is added to the copper in the flask. The mixture is heated. The heated air expands, and is pushed out of the flask. The copper reacts with the acid. One of the products is sulfur dioxide gas, which fills the flask. After the heat is removed, the gas in the flask cools, and contracts, drawing water into the flask. Initially, the water vaporizes due to residual heat, and expands rapidly. Again it cools, and water is drawn again into the flask. As water enters the flask, the sulfur dioxide gas evolved in the reaction dissolves. The pressure in the flask is reduced, which draws more water into the flask. When a concentrated solution of ammonia is added, the copper(II) ion in solution reacts to form a complex ion, which is blue in color. The previous paragraph explains the procedure needed to get blue color from copper and sulfuric acid. I think I'll skip the final step which is adding the concentrated solution of ammonia. Unfortunately, that's how you get the blue stuff to confirm its copper. I don't think the sulfuric sold at the local hardware store is concentrated enough either. I am thinking whomever wrote that has never tried it. None of the gas evolution happened nor was the heat required in my copper plating bath. The stuff from the hardware store is 3/4 strength if memory serves. Nonetheless, it doesn't address my suggestion that a drop of sulfuric probably reacts with copper arsenic compound to make a blue color. Did say probably. Not discussing production quantities. Just a tiny qualitative test. But, thanks for being safety police. If you want to play with concentrated ammonia, you have my permission You neglected to mention that you got the blue from electroplating which is entirely normal. Upon further research online I did find this.... Why does the sulphuric acid turn blue when copper ore is added? I performed an experiment at school today and after we added sulphuric acid to copper ore and stirred it for a while, the water became murky and blue. I need to write an analysis for this experiment and I was just wondering HOW or WHY did the water turn blue? So, there is some proof online of this and what you say is entirely correct. It will do what you say (after stirring for a while.) I don't think I would reject it as being a copper arsenic compound if the acid did not turn blue by adding a couple of drops of it to the sample. A better way to tell for sure what it is would be a streak test, as you have already suggested, the exact match in S.G. (which it has,) the exact match in mohs hardness (which it also has,) and by just looking at it visually.
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Deleted
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Post by Deleted on Sept 8, 2016 10:01:42 GMT -5
ziggyIt turns blue because copper sulfate is inherently blue. You must teach high school chem. Your ammonia quip is uncalled for.
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ziggy
spending too much on rocks
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Post by ziggy on Sept 8, 2016 10:05:43 GMT -5
ziggy It turns blue because copper sulfate is inherently blue. You must teach high school chem. Your ammonia quip is uncalled for. Nothing malicious meant there...sorry. You and I obviously have different senses of humor (or you got up on the wrong side of the bed.) The safety police comment was uncalled for as well which is what spawned my permission to use the ammonia. You're forgiven. You missed the point of what I wrote. The following was a quote from a website: Quote:Why does the sulphuric acid turn blue when copper ore is added? I performed an experiment at school today and after we added sulphuric acid to copper ore and stirred it for a while, the water became murky and blue. I need to write an analysis for this experiment and I was just wondering HOW or WHY did the water turn blue? End quote: Notice. It is not me asking you the question. It is a student asking the question to people online. It was not me in school, it was a chemistry class student. He was asking others to help him find the answer to his question. I was using his quote to re affirm that yes, indeed, sulfuric acid WILL turn blue when mixed well with copper. So, in effect, you are correct on that point. Getting back to the subject at hand in this thread I would still not rely on the results of a couple of drops of acid which might not do anything at all without mixing as a definitive judgement on if there is copper there or not. I personally have been out of school for over 40 years (not counting college), and teach no classes. I realize that I'm new to the forum, but not to rockhounding which I've done since I was a little girl. I might know as much as any expert for all you know and I might have a degree in geology from college.
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Deleted
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Post by Deleted on Sept 8, 2016 11:00:11 GMT -5
ziggy It turns blue because copper sulfate is inherently blue. You must teach high school chem. Your ammonia quip is uncalled for. Nothing malicious meant there...sorry. You and I obviously have different senses of humor (or you got up on the wrong side of the bed.) The safety police comment was uncalled for as well which is what spawned my permission to use the ammonia. You're forgiven. You missed the point of what I wrote. The following was a quote from a website: Why does the sulphuric acid turn blue when copper ore is added? I performed an experiment at school today and after we added sulphuric acid to copper ore and stirred it for a while, the water became murky and blue. I need to write an analysis for this experiment and I was just wondering HOW or WHY did the water turn blue? Notice. It is not me asking you the question. It is a student asking the question to people online. It was not me in school, it was a chemistry class student. He was asking others to help him find the answer to his question. I was using his quote to re affirm that yes, indeed, sulfuric acid WILL turn blue when mixed well with copper. So, in effect, you are correct. Getting back to the subject at hand in this thread I would still not rely on the results of a couple of drops of acid which might not do anything at all without mixing as a definitive judgement on if there is copper there or not. I personally have been out of school for over 40 years (not counting college), and teach no classes. I realize that I'm new to the forum, but not to rockhounding which I've done since I was a little girl. I might know as much as any expert for all you know and I might have a degree in geology from college. Yes, wrong side of bed. Sorry.
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Post by mohs on Sept 8, 2016 19:02:28 GMT -5
Last night I dreamt I was playing sand lot baseball. Like I did when was kid With only 3 or 4 players in the field I had a really great bat & got a beauty of hit. Out to right center field! As I was rounding 1st base I asked where the scotch tape was at? Ya see first base was a piece of paper. Then I saw that 2nd base was open I made a dash for it. I slid in head first in! Hand just touching the corner of the paper plate bag. Safe!!! Then I woke up! I was on the ground face first. Boom! I hit pretty hard! It took me awhile to dust myself off get back to sleep. Mohs
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