Edge Posted April 9, 2019 Share Posted April 9, 2019 I believe I picked this up in the Belmont mtns. Very heavy, black streak test, not in the least bit attracted to a magnet. I took a grinder to it which did little but polish a bit. No sparks, didn't fracture or leave dust. Not ilmenite, magnitite or graphite. Probably something obvious designed to trip me up. above is where I used the grinding wheel. Quote Link to comment Share on other sites More sharing options...
Sonoran Dave Posted April 9, 2019 Share Posted April 9, 2019 I'm guessing a variety of copper sulphide. Maybe chalcocite, or even covellite. I have a chunk of covellite here, that is so dark indigo... it's almost black. Since the picture makes it look grey, I'd lean towards chalcocite. 1 Quote Link to comment Share on other sites More sharing options...
Edge Posted April 9, 2019 Author Share Posted April 9, 2019 4 hours ago, ArcticDave said: I'm guessing a variety of copper sulphide. Maybe chalcocite, or even covellite. I have a chunk of covellite here, that is so dark indigo... it's almost black. Since the picture makes it look grey, I'd lean towards chalcocite. Covellite leaves a grey streak though. Going with chalcocite. Now, where's my acids, hmmm 1 Quote Link to comment Share on other sites More sharing options...
Bob(AK) Posted April 10, 2019 Share Posted April 10, 2019 How hard is this piece? Both chalcocite and covellite are quite soft and both will ring loudly on a detector. The top photo looks brown on the end is that so? Quote Link to comment Share on other sites More sharing options...
Edge Posted April 10, 2019 Author Share Posted April 10, 2019 It's very hard, not black but gives off an interesting silver/ blueish metallic hue. I read chalcocite is mildly magnetic when heated. ..hmmm Quote Link to comment Share on other sites More sharing options...
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