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Found this in abundance,need help to i.d please?


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Ok first and foremost I'd like to say thank you in advance for taking your time to examine my specimens.currently I have about 250 pounds of this stuff, I don't know what it elements are present. I do know that it is not magnetic although if turned into dust and you have a very strong magnet it will attract slightly,it does not react in muriatic acid,it does react in hydrogen peroxide moderately,

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It's obviously some type of metallic sulphide. Is the streak black or gray? That might help narrow it down.

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It's the mineral Stibnite. It's the sulfide of the element antimony, a toxic metal. The ore sells for less than $100 a ton but good crystal group specimens can sell for quite a bit.

It looks like it's in a Siderite (Iron Carbonate) matrix, this is a common association with Stibnite ore. The Siderite being a carbonate is where the hydrogen peroxide bubbling came from.

Edited by clay
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If it is/has stibnite in it, easy way to tell is to take a small splinter in the flame of you r lighter.  If stibnite is present, the splinter will fuse or turn into a melted ball.  Stibnite has the lowest fusion temp of nearly all minerals.  On the geo fusion scale, stibnite is 1.

I agree with another, this looks like a massive sulfide deposit. 

Could also have arsenic in it.  Rub against a hard metal an see if a "garlic" odor is present.  If it does, it has arsenic.

If you try the fusion test, see if you detect a "sulfer smell" from the sample.   If you smell sulfur, its a sulfur salt.

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Stibnite found on the California coast has a strong association with arsenic (Realgar) and mercury (Cinnabar) minerals. Applying an open flame to the sample in an unventilated space may produce unhealthy fumes.

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Thank you all for your input, it is much appreciated. Yes it is very heavy for its size and I'm going to give it a fusion test 

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5 minutes ago, Dvus925 said:

Thank you all for your input, it is much appreciated. Yes it is very heavy for its size and I'm going to give it a fusion test 

Let us know the results.

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This is before,during,and after the fusion test with a paper  thin piece of material

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Not so much as a pop,flick or snap like when pyrite is heated not a ball or bead of any sort and I got it red hot 2 and a half minutes of propane and it looks a little yellow but all there?

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No garlic smell either i had a chance to hit it with an  acetylene and oxygen torch and a bead dripped off the vise that was holding it it was silver in color with a dull pink tinge to it I hit it with a hammer and the bead was hollow

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In the area I found this ,approximately  within 15 feet I found this in the ground its about 48 inches round and buried about 3 feet down

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3 hours ago, Dvus925 said:

Thank you all for your input, it is much appreciated. Yes it is very heavy for its size and I'm going to give it a fusion test 

There's a test called XRF that jewelers, pawn shops,prospecting shops have on hand for elemental ID. A search in these forums for XRF will explain it.  It is inexpensive.

I wonder if acid plumbing flux would help the smelting effort?

As stated earlier, you should have lots of ventilation and preferably  a n100 fume respirator. Antimony is more toxic than lead, I believe.

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We can run out stibnite; would have fused easily at the tips of the sample.  For future reference, when doing a fusion test, use a sample that is just big enough to be handled with by tweezers.

Strike the sample with hammer to see if there is a garlic smell.

If you have a piece of unglazed porcelain, rub the sample against it and then smear out the streak out.  Take a clear photo to show us.

A hardness test would be helpful.  Do you know how to do a Moe's hardness test?

You have tried Hydrochloric acid to dissolve it with no reaction.  Do you have some sulfuric acid (battery acid)?  If so, carefully, & out side,  see if a small sample with dissolve in a small bit of battery acid (a few sample grains 1/2 the size of a BB & 3-4 eyedropper drops of acid)  The other acid used for testing is nitric acid, but most do not have access to nitric acid.

Can you tell us what county/town, in Calif the location is near?  That would help narrow things down without giving away the location.

Edited by 4meter
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The original poster did provide information on reaction with hydrochloric acid (none) a streak test (dark gray/metallic) and crystal form:

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We also know a carbonate is involved (bubbling when exposed to hydrogen peroxide).

A hardness test should be helpful.

Edited by clay
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Well, based on what we know so far, and after consulting my minerology books;  I would place this sample in the arsenic sulfide group.  Maybe Arsenopyrite (best fit so far), Cobalite or Skutterudite (that really is a mineral name). 

All of these have a metallic luster, gray-black streak, silver gray to silver white color, 4.5 to 6 Mohs hardness, not fusible, will not react with HCl, all tend to be massive in sample view.  Now, if we had some nitric acid and could do a bead test, we could pin it down to one of the above.

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51 minutes ago, 4meter said:

Well, based on what we know so far, and after consulting my minerology books;  I would place this sample in the arsenic sulfide group.  Maybe Arsenopyrite (best fit so far), Cobalite or Skutterudite (that really is a mineral name). 

All of these have a metallic luster, gray-black streak, silver gray to silver white color, 4.5 to 6 Mohs hardness, not fusible, will not react with HCl, all tend to be massive in sample view.  Now, if we had some nitric acid and could do a bead test, we could pin it down to one of the above.

All that would be true if only these samples were purely one mineral. As you know these hydrothermal deposits are virtually always composed of complex polymetallics. The common associations in California coastal deposits include arsenic, mercury, lead, copper, silver and antimony sulfides. Seldom do these sulfides exhibit any particular pure mineral examples except in obvious crystal formations.

When I first started studying minerals in the 1950's and 60's crystal forms were the most dispositive evidence of a particular mineral. We didn't have XRF or qualty color photos to help. Of course crystals are relatively rare in these sulfide deposits but it's a sure bet that if there is a mineral crystal it will either match the angles and growth habit of the mineral it is composed of or it will be a psuedomorph of a previous crystal form.  With this sample we do have an obvious intact crystal grouping. I don't see the crystal forms for arsenic, mercury, copper, lead or silver sulfides but I do see a crystal form that appears to be a reasonable match for the antimony sulfide Stibnite.

Other than that I have nothing but the appearance of the broken sample and what appears to be a dark gray metallic streak. It's just an observation leading to an educated guess which is all we can do with the information provided.

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The services of a professional assayer would be the next step if the original poster would like to know if there is anything of value and how much per ton.

The samples my be just pyrite with minor amounts of other metals; just enough to produce other colors in the sample beside the normal brassy color of pyrite.  I have pulled samples of pyrite from the ground that looked "silver".

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