Found a pretty good spot, but it was hard won gold. Took me a few hours bush bashing the dredge in… then getting it out again at the end. Gold dredging boot camp keeps you fit!
The bigger bits, all sub-gram. Heaviest bit was 0.6 grams:
They stayed with the gold while cleaning and sounded the same as gold when dropped on the pan. Pretty shiny, no dullness at all, so I’m guessing they’re not mercury amalgam. Being in the river for a while I’d expect any mercury amalgam to be a bit dull?
Had a good search online for scheelite images, and I don’t think it is. But it did look similar to platinum nuggets that came up on an image search. So I’m leaning towards platinum at the moment. I can wish Now I just need to find some bigger ones!
Hi Gavin. I’m thinking cassiterite (Tin Oxide). or arsenopyrite.(not to be confused with common pyrite). I do lean towards arsenopyrite as that is a more common mineral found on the West Coast, mostly associated with quartz reefs, many gold bearing. Cassiterite is a somewhat rarer mineral on the Coast only found in a few isolated occurrences in stream material. Kiwikeith it has been reported as being found in Stevensons Creek, over the back of Denniston, and I can confirm that as I dredged in Stevensons and did find cassiterite. It was somwhat oxisdised and was blackish silver in colour. .I have found gold bearing arsenopyrite in Bourkes Creek, near Reefton, also dredged there. It was very fine, being contained in stamp mill tailings (flour) from the Inglewood Gold mine situated at the head of Bourkes Creek. Also Google images of arsenopyrite are identical to your samples Gavin. . .
Cheers for that @kiwigold but I’m still not 100% sure. The bits I have definitely look a bit more metallic with worn edges, rather that crystalline with sharper angular edges. Arsenopyrite looks more likely out of the two suggestions though.
Gives me a few more possible candidates though!
Piqued my curiosity as I’ve done a lot of dredging in the area, but this is the first time I’ve noticed the silver looking pieces in the fines before, remaining after final clean-up.
Ah ha. why didn’t I think of this one yesterday. Try Stibnite the ore of Antimony (SB) always associated with west coast gold bearing reefs.Esp around Reefton where it was actually stock piled if a market could be found for it.(Printing industry) The miners used to hate it. it floured the mercury on the tables. Resulting in much gold loss. The cyanide process stopped that problem. Does not always have a crystalline appearance. If you ever go gold detecting in Murray Creek at Blacks Point, near Reefton, the stuff will drive you mad. .
Hmm, looks like a maybe, but I’m wondering if the specific gravity of stibnite is a little low to let it remain with the gold and not get washed away with the iron sands and other chaff during clean-up? But iron sands have only a slightly higher specific gravity than stibnite, so maybe it could be a match.
Thanks again for the suggestion though. I’m certainly learning a bit about minerals I never knew existed before!
I was told by a geologist in golden bay that the only platinum deposits found in New Zealand are in the Nelson area in a small specific belt line, the whole area is under research by geological sciences students from Canterbury university apparently?
The mining company in the article seemed interested in employing West Coast residents though, suggesting it had an interest in possible platinum in the area.
I spent a few years as a metallurgist on a platinum mine in south africa. On our shaking tables the meatllics were split out in to clear lines, while hild is always shiny platinum is always dull grey. So doubt if its platinum.
Now I just need to find some bigger ones!
