Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: granite7 on 16/06/2010 03:59:49

Title: ?Gold or Pyrite?? See photos!
Post by: granite7 on 16/06/2010 03:59:49

Ok, I read all the threads on gold identification. But I still need an expert eye to give me some more incite. So here's some pics. I determined that it is not magnetic and I did a muriatic acid test too. No dissolving took place. This sample is from an area rich in Paleozoic mixed rocks and adjacent to a gr^Mz zone Mesozoic Plutonic rock. Not sure if this info will help or not, but maybe the photos will clarify a little. I called the college geology dept. here locally, but they don't do testing. So any advice before I take it to an expensive lab?(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2F&hash=3cd4f4119996b42d10f5ed9eb0e8d712)

Title: ?Gold or Pyrite?? See photos!
Post by: JimBob on 16/06/2010 17:58:11

It is POSSIBLY gold ore but it MIGHT be. The gr^MZ means granite-Mesozoic.

If you have a broken piece of crockery or the underside of a dinner plate that has a rough surface try to see what sort of streak you get if you pull the rock across the rough edge of the porcelain.

This could possibly be but ... well, having been in Southern California there is just not much gold in Ventura County.

BASS ?????   

GET OFF THAT OUTCROP AND GET IN HERE!  WE NEED YOU!

(He is the mining expert. Need to shout real loud in Montana)

Title: ?Gold or Pyrite?? See photos!
Post by: RD on 16/06/2010 18:23:54

sharper ...

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Title: ?Gold or Pyrite?? See photos!
Post by: Geezer on 17/06/2010 06:48:39

Hi!

I'm sure I can help.

Please send me a personal message with the precise Lat/Long coordinates of the location where you found this sample.

Do not post the coordinates on this forum. I'm not naming any names, but some of these people are not to be trusted.

Title: ?Gold or Pyrite?? See photos!
Post by: RD on 17/06/2010 15:55:03

Looks similar to this pyrite on coal ...

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Title: ?Gold or Pyrite?? See photos!
Post by: frethack on 17/06/2010 16:22:51

Is the rock flakey by chance, or does it look like its made from deformed sheets?

Title: ?Gold or Pyrite?? See photos!
Post by: Bass on 17/06/2010 23:16:31

Welcome to the forum, granite7
Hard to tell from the photos.  Gold is distinguishable by its very bright gold color, weight, malleability, hardness and lack of oxidation.  Pyrite is not as dense, is less bright, tends to be brassier colored, forms cubic or pyritohedron crystals and oxidizes to yellow/orange/red/brown or black coating.  You can't scratch pyrite with a knife (but may be able to scratch oxidation products coating pyrite).  Pyrite is not magnetic (pyrrhotite is- but is more silvery).  Could also be chalcopyrite.  Oxidation in second picture makes me think sulfides are more likely than native gold.