If there is gold there it is most likely to be I the form of a gold sulfide within the pyrite. If there is a high percentage of gold in the sulfide it can be crushed and panned out to verify. Back in the day the gold sulfide was burned off and it releases all kinds of nasty chemicals into the air. Anymore it is often chemically treated in leach ponds and froth flotation. I have several buckets of ore that look similar to your photos. I was able to crush the rock into a powder and pan out some free gold and a lot of the sulfide that most likely contains some gold

Very nice samples of mineralized fault or shear zone.  Can you follow along strike and does the material stay the same or change?  If you're on a vein, have you sampled the edges and also the surrounding rock?  An assay is the best way to be certain of what's there.  Make sure they do a sulphide assay.  If you have native gold present you can crush and pan but if it is molecular and tied up within the pyrite you will likely be further ahead to have it assayed and sell the location to someone with deep pockets.  Do you have enough material to sell any for a rock garden?   Have a great day.

I have a similar issue too, which the material looks like pyrite but also like gold. However, if there is native gold present in the sulfide and it can be crushed and panned out, how can you tell if the remaining material might contain smaller gold?

Leo, a sulphide assay done correctly would tell you if you had Au locked within the pyrite matrix. Are the 6 pictures all from the same location? 3 of them look like graphitic schist w/pyrite(sulphide). Can't tell if the one pictured above is the same material.

Allan,

The one pictured here is not the same as the ones you mentioned as being graphitic schist. I found this in a huge tailing pile from old mine workings. Its not too great of a picture, its not showing the golden sections much. The mineral seems to be a coating or layer on the rock, with rusty (oxidized iron?) material. What is actually a "sulfide" assay....is it different than others? I checked with a local place in Nevada and they want $300 for minimum charge. ( I forget how many samples I can submit). Is that a fair price?

You mentioned the graphitic schist.....I broke this off the side of a hill...it breaks apart very easily, and yes it seems to have a lot of pyrite in it. I didn't know what it was, thinking maybe it was oxidized silver. I tried to heat with high temp to see how it reacted. Where I found this material, there is a visible golden seam or vein, but it seems that it has much of the rusty color. Is gold ever found in material like this? If its in the sulfide, probable the only way to get it out is leaching?

Regards

 

 

Heating has potential to release toxic gases and be lethal.  If any greenish tint near the sulphides it could have some arsenopyrite which has arsenic poisoning potential.  An assay is the first step to let you know what potential problems could be in the rock.  Leaching without the proper set up will create toxics like heating and without proper disposal can poison others.  Are there any larger mines in your area you could ask info from?  They also would have the apparatus and funding to work the sulphides safe and profitably if rich enough.  I'm not good with computers, is there a way to view your post while I am answering it?  If you had access to someone with a rock saw you could cut a section out of the rock to look at flat with a loupe or preferably with a microscope.  Pyrite is brittle and Au is malleable so you could pick and prod the slab to see how you're golden flashes react looking for the larger native Au.  The photo posted almost looks like a metamorphic gneiss.  Have you crushed and panned either of your samples?  Wear protective breathing apparatus while crushing and pan into a containment tub.  You should get a floating dark scum that will contain sulphides.  Happy Diggin

 

Take your thumb nail and try to crush the so called seen gold.. does it break off or chip? Pyrite... Does it dent? Gold.. Some assay labs have a min of like you said 300 bucks I know of one in Reno that is like that but there are other assay labs you can mail it to for 40-60 bucks and get results. If it were me I would run it in a good crusher and pan it out to start. If you keep finding samples like that or are following a vein then get an assay.

My understanding was that if it was oxidized it would be free gold and visible to regular eye, but if its a sulfide then it would be more microscopic gold locked up in the host material and not at all visible? Does anyone know if that is a safe assumption?

The pictures that you call graphitic....that material is very crumbly and soft and was found exposed under oxidized material (scrapping away a few inches of top cover on a wall at the mouth of an abandoned mine) Since it was in an area known for silver as well, I thought maybe it was ore that wasn't worth commercial interest.