SnowProspector Posted February 8, 2020 Share Posted February 8, 2020 I came across some rustbrown colored mica schist and decided to scan it with my Garret At gold with a double D coil. I'm im all metal mode, ground balanced and the detector starts to give me a lot of targets with 60-80 on the scale(thick gold/precious metal). Iron is below 30-50. I hammered out the rock that was giving me the high reading and it turns ut there is thick layers of some dissiminated metallic (?) layer in the schist. Is have had a closer look and it does not look like pyrite because it is quite dark gray, but still has the metallic shine. It is brittle, so not sure if it is metall or sulfide. I heard several people say that sulfides do not give a reading on a metal detector. To confirm that i have testes a big chalcopyrite that gives absolutley no noise on the detector. I also have a 14 lb chunk of stibnite that also gives no sound at all. Then this wierd rock gives a strong 80 gold/Silver Reading. Have anyone had sulfides make a strong reading? I added pictures of the metal/sulfide that i hammere out. What do you think? Link to comment Share on other sites More sharing options...
Steve Herschbach Posted February 8, 2020 Share Posted February 8, 2020 Too out of focus but at a guess I'd say arsenopyrite, a sulphide, and highly conductive. Second guess graphite. If it will easily mark up paper go with graphite. Whether some magnetic minerals sound off or not depends on the ground balance setting. Others that are conductive, like arsenopyrite, will pretty much beep no matter what. I have found many pounds of arsenopyrite while metal detecting so toss the sulphides are undetectable theory. It just depends on the sulphide. 5 Link to comment Share on other sites More sharing options...
oldmancoyote1 Posted February 9, 2020 Share Posted February 9, 2020 Without a better focused image, it's hard to tell. From what I see, it appears black. The arsenopyrite that I am familiar with is usually a lighter grey color, but wikipedia shows some black specimens. It could be a tellurium gold mineral called Calaverite. If so, it's dangerous. Heating it will emit poisonous fumes. Calaverite In general when submitting photos for mineral id, sharp focus is very important, and scratching it with a knife can leave useful clues . 1 Link to comment Share on other sites More sharing options...
SnowProspector Posted February 9, 2020 Author Share Posted February 9, 2020 Thanks guys! That is interesting! So we have sulfides that appears as metal and others dont make a sound. Will arsenopyrite get above your Iron discrimination too? I did not expect sulfides to do be classified as +-80 (gold/Silver). I came across a piece of basalt that gave a loud and clear signal but not a number on the metal indicator. How to you go about classifying mineral? Microscope? Send in a sample? What does it cost? Rent an xrd tester? -E Link to comment Share on other sites More sharing options...
Jim McCulloch Posted February 9, 2020 Share Posted February 9, 2020 Black, semi- metallic, semi-crystalline, reads high on the scale, start considering a silver ore complex. 2 Link to comment Share on other sites More sharing options...
GB_Amateur Posted February 9, 2020 Share Posted February 9, 2020 7 hours ago, SnowProspector said: How to you go about classifying mineral? Microscope? Send in a sample? What does it cost? Rent an xrd tester? These people advertise in ICMJ. I sent in some chips to them for $25 X-Ray Fluorescence (XRF) analysis. The (in)consistency between sample readouts seemed extreme to me, although maybe that is typical. 1 Link to comment Share on other sites More sharing options...
SnowProspector Posted February 9, 2020 Author Share Posted February 9, 2020 4 hours ago, Jim McCulloch said: Black, semi- metallic, semi-crystalline, reads high on the scale, start considering a silver ore complex. Thanks! I have been thinking(hoping) that it could be some more exotic metal. There is a Company that renta out XRD gun where I live. I will Contact them for a quoate. -E Link to comment Share on other sites More sharing options...
Steve Herschbach Posted February 9, 2020 Share Posted February 9, 2020 Take it to a local rock club or school geology department. Of post a really sharp photo. Link to comment Share on other sites More sharing options...
fredmason Posted February 10, 2020 Share Posted February 10, 2020 XRF machines must be calibrated correctly. They require some specific procedures to be accurate.... but it ain’t my money fred Link to comment Share on other sites More sharing options...
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