Post subject: Re: Stones from a goldmine in the Philippines
Posted: Fri Mar 06, 2015 12:04 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Congratulations on getting additional information to post. Let's do some hardness tests too. A pen knife is a good place to start. Also a scratch plate, which is just a white piece of unglazed tile. Scratch the unknown. What color is the scratch.
Post subject: Re: Stones from a goldmine in the Philippines
Posted: Fri Mar 06, 2015 6:25 pm
Gemology Online Veteran
Joined: Sat Jul 14, 2012 5:11 pm Posts: 657
Hi Musse, gemstones, I think not, but common host material from a gold/silver/lead/zinc deposit. All have small gold inside? I doubt that, although they may have finely disseminated particles, like maybe a few PPM, (parts per million). You can be assured that these specimans have no commercial value, but look good as garden edges. I have had success, years ago, with cutting similar stuff from a gold mine I was involved with, into big cubes, using a large diamond saw. Sold them as book-ends, and they went well. Watch out for lead content though, also check the mine chemist to see if Arseno-pyrites are involved. They are dangerous for your health!
Post subject: Re: Stones from a goldmine in the Philippines
Posted: Mon Mar 09, 2015 4:46 pm
Gemology Online Veteran
Joined: Sat Jul 14, 2012 5:11 pm Posts: 657
Of course they are going to dig a pit Musse, that's what a mine is. The host rock for the gold looks to be an altered quartz complex, and probably in conjunction with epithermal gold deposition. In other words, hot volcanic solutions have deposited materials. If it is a working mine, why not ask the mine geologist for answer to your question? Once again, P.P.M gold could possibly be present. Current gold prices mean the sort of levels that were being mined a few years ago, are now sub-economic, and many mines are now closing. What you show is commonly seen on mine dump sites. Barry
Post subject: Re: Stones from a goldmine in the Philippines
Posted: Tue Mar 10, 2015 5:11 pm
Gold Member
Joined: Sun Jun 28, 2009 9:56 am Posts: 1284
when tested with HCl, if the turquoise stone did fizz then it could be calcite or aragonite
the first red stone is some typê of quartzite
the second one associates white quartz, golden/silvery sulfide (likely pyrite, marcasite or chalcopyrite) and some grayish-black stuff which could be either an alteration of the previous sulfides, or a different sulfide mineral (mindat has a list of sulfides found in the Philippines).
Making the difference between marcassite, pyrite, chalcopyrite and gold is easy. Pyrite and marcassite scratch glass while chalcopyrite and gold don't. Gold is malleable, while chalcopyrite is not.
Also note that in gold mines, gold isn't necessarily present as visible grains/veins: in many cases the gold is only found as microscopic inclusions within sulfides minerals or quartz.
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