Whats The Gold Grade 24k? Of Most Nuggets Found These Days Around Globe?

[idahogold]

Sittn here thinking about my "test" nugget 2.7 gram chunky solid bit I "bought off ebay to test my GB2/gpx45/sdc23 with.....I'm a newbie ' but have watched nuggetdiggs" on youtube . and watched thousands" of vids in 9 years! Thats Alot of Gold coming out of the ground! But it never crossed my Mind till tonite......Whats the Grade??? And how does the Western US compare to Australia, Alaska, Africa? My little noug' looks light yellow slightly silvery  14k-16k i'd guess  supposed to been found w/ a metal detector in,Nor.Cal. "Must be Dale's Hands from Goldhounds ...Made it myscreensaver " last nite! Is All gold mostly higher grade than what i got for $165 shipped off ebay?.........just wondering? Thanks from central Idaho-JD

[Ringmoney]

Over here in Ireland they range from 21k to 23k depending on where they are found. The ones found in the stream beds are higher than ones found in fields around because the "other metals" alloyed in it get leached out over thousands of years.

[klunker]

  I have nuggets from .956 to less than .800. But I have to ask what difference does it make when it comes to nugget hunting? If you are selling nugget gold, the price is more dependent on size and character than purity. My last sale to a refiner was .860 which is probably a bit above average. Ringmny is right on about impurities leaching out of a nugget. A scratch test my show a higher purity on the outside than what the nugget may actually be inside.

[Steve Herschbach]

The mining world does not usually use the karat scale when talking about gold purity. Gold is discussed in terms of "fineness". The scale runs from 0 - 1000. For example, gold might be said to be 830 fine, which is the same as 83% gold. 842 fine would be 84.2% gold. There being no such thing as absolutely pure gold gold bars will be stamped 999.99 fine.

Natural gold in the 900 range would be high purity gold, the 800 range more the average run of the mill stuff, and under 800 low purity stuff. The lower purity types are sometimes referred to as electrum.

Alaska has average purity gold in general but in reality all types can be found. California and Australia are noted as having high purity gold. Nevada gold is usually average to lower purity with electrum not uncommon.

Reports like this can be Googled:

Fineness of Gold from Alaska Placers by Philip S. Smith
1937 USGS Bulletin 910-C
http://www.dggs.alaska.gov/webpubs/usgs/b/text/b0910c.PDF
Accompanying map http://www.dggs.alaska.gov/webpubs/usgs/b/oversized/b0910cpt03.PDF

[fredmason]

just as an aside, a jeweler was telling me that many countries stamp the gold purity in numerals rather than Karats...something I did not know until he told me...I always thought purity in numbers meant it was silver...

fred

[Au4Gold2]

Gold I have found in my county  in California so far has a range form 18kt or 750 to 23 karats or 96.50 % pure. The real pure stuff 23 karats comes from one spot and I could not believe it myself until I had it tested at a jewelry shop. 

[Reno Chris]

Actually, gold can vary even within the same deposit. Even where most of the gold is fairly high purity you can get some nuggets that are much lower. Color is not a perfect key to tell you what you need to know, but it does tell you something. The upper two in the picture below are both from a spot in Nevada where Steve and I were chased out by rain recently. Nevada does produce some nice gold of at least average purity. The lower three are electrum. The one on the left is from California from a deposit where all the rest of the gold was typical California buttery yellow except this little chunky nugget. The one lower middle is from Nevada, a mining property where a guy asked Steve to evaluate for its metal detecting potential (It was the only piece we found); the lower right is a piece from a spot that has produced some nice wire gold for both Steve and I, but all the rest that we've found there was a nice yellow in color.

A friend recently found a nice piece of ore on an old mine dump. It was heavy and a geologist friend of his cut it open and made a few slabs out of it. It is shot through with silver. He showed me some photos and I know the mine it came from. Almost all of the true native silver is formed by secondary processes (processes related to weathering and natural chemical alteration); this ore specimen is primary, so I told him it was unlikely native silver but instead high silver electrum. He told me the geologist had told him the same thing. The geologist is going to get it tested by probe as a favor. They touch it with a XRF probe and get a reading of what the purity is.

[Au4Gold2]

"Actually, gold can vary even within the same deposit"

 

Interesting, did not know that, thanks Chris...Chris is it possible to have gold purity even higher than 98% in its natural unrefined state in California? 

[Reno Chris]

Gold naturally more than about 95 or 96 percent is very unusual. I know of some as high as 98+ percent pure from Australia, but none from here. The highest purity gold is formed by secondary alteration often from gold tellurides.

Gold formed at hot temperatures down in the earth can contain more silver and other stuff, if formed at the surface of the earth (as a secondary mineral) it just cant hold the same amount of silver, and as a result its higher purity. The same is true for silver - if grown at surface temperatures it can't hold as much impurities. If grown hot it can hold much more in the way of impurities. 

[Steve Herschbach]

It is also very common for silver to leach out of the surface of nuggets, resulting in a thin but purer "rind" of gold on the surface of the nugget. This is seen when jewelers buff a naturally gold nugget, and it turns a lighter gold color when the rind is buffed off. It also can give misleading readings of the overall purity of the nugget if only the original natural surface of the nugget is tested.

COMPOSITIONS OF PLACER GOLD IN THE RAMPART-EUREKA-MANLEY-TOFTY AREA, EASTERN TANANA AND WESTERN LIVENGOOD QUADRANGLES, CENTRAL INTERIOR ALASKA, DETERMINED BY ELECTRON MICROPROBE ANALYSIS
by - 
R.J. Newberry
Department of Geology
University of Alaska-Fairbanks
K.H. Clautice
Alaska Division of Geological & Geophysical Surveys
Download at: 
http://www.dggs.alaska.gov/webpubs/dggs/pdf/text/pdf1997_049.PDF