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16,328 users

what mineral is This?

0 votes

there is a mineral that I cant Identify . it has a dark grey-black color and metallic luster with greenish streak color . its hardness must be around 4.5 but Surely its above 3.5 . it has a granular Aggregation . limonite and gothite can bee seen around it as well as quartz . alt text

asked Aug 5, 2012 by Tarja (200 points)

8 Answers

0 votes

Looks like some some sort of ore material. Where does this material originate? Could it be pyrite?

answered Aug 6, 2012 by hershel (51,320 points)

I cant exactly say but it looks like is a hydrothermal vein in Metamorphic rocks ( slate , phyllite ...).in the rock limonite and gothite and different types of quartz can be seen too. it has a light green streak color so I dont think about pyrite (pyrite has dark green-black streak).what do you think about chalcopyrite or malachite? I upload an image that may be use full. the granular brassy- dark green!

0 votes

Can you try to upload some close-up pictures so we can get a better view?

answered Aug 8, 2012 by hershel (51,320 points)

This is the best Pic I can take.

alt text

0 votes

Hard to tell since its a bit blurry, but it looks like there is iridescence there. Could be arsenopyrite. Did you try a streak test?

answered Aug 9, 2012 by hershel (51,320 points)

as I said before it has a light green streak

0 votes

It looks more metallic and is unlikely malachaite. Chalcopyrite also has a green streak so that would be a good guess.

answered Aug 14, 2012 by hershel (51,320 points)

yes I think it may be Chalcopyrite. thank you hershel.

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Chalcopyrite also has the iridescence, so it makes the most sense. I have seen chalcopyrite just like this in hydrothermal veins in the Ellenville Mine in NY.

answered Aug 14, 2012 by hershel (51,320 points)
0 votes

could be feldspar, apatite, but definitly not malichite

answered Aug 15, 2012 by zephyrfrog (140 points)
0 votes

I know this rock, or at least its metamorphasis into the colors that are displayed. I also have one like it. The red through yellow colors are the result of either arsenopyrite, ruby silver (silver antimony arsinide) or sperrylite (platinum arsinide). Not much value as a mineral specimen if it is just arsenopyrite but the other two are very pricey.

Test for silver by roasting then reducing a piece of the metalic crystal on charcoal. If ruby silver it will leave a silver ball. If platinum group then it will leave a silver-grey poreous crust. If arsenopyrite perhaps a white powder, 'tho arsenic is quite volatile so you will probably blow most away with the torch. Do this outside and use a small piece. Arsenic is a poison; smells like garlic.

Sperrylite ore is very heavy. If it contains sperrylite then the specific gravity should be over 7.

There are other tests but the low melting point of silver and the unmeltability of platinum with a propane torch should suffice.

A big clue is the geology in which it was found. If in ultramafics (dark, basic, deep seated mantle rock, usually not surface flow like basalt or felsite) such as the Sudbury or Manitoba nickel belts then it is probably sperrylite. Also could be sperrylite if found in pegmatite, serpentine or olivine-rich rock. 99% sure it's arsenopyrite if found in scarn or carbonate rock.

Dusty Roads (40+ years a Canadian Prospector) http://lottocheatah.com/platinum/ruby9.jpg image

answered Sep 30, 2012 by Dusty Roads (140 points)

I should add that arsenopyrite contains iron. With the torch test if arsenopyrite it will leave a black lump. If iron it will jump onto a magnet when passed over it. If platinum it might wiggle, no more.

There has been some comment about it being chalcopyrite, bornite or some copper mineral. A sure test for copper is to dip a piece of the metalic crystal in hydrochloric or sulfuric acid and then hit it with the torch flame. If it contains copper you will get a brilliant azure blue flame coming off of the sample. Muriatic acid from the hardware store or car battery acid will also work.. only need a drop. Try it on a piece of copper wire. You will see what I mean. Unmistakable test for copper.

0 votes

thank you Dusty Roads. I will Do what you have sayed and tell you about the result.

answered Oct 2, 2012 by Tarja (200 points)