Raw placer gold is never pure. How impure it is decides most of what you get paid — and it is the number buyers are most likely to assume rather than measure.
Placer gold commonly runs 70% to 95% gold, with silver making up nearly all of the balance. The trade measures this as fineness: parts of gold per thousand, so 890 fine is 89% gold. Fineness depends on the deposit, not on the size of your pieces.
These are published USGS and Alaska DGGS assay summaries. Note the spread — within a single region, fineness varies more than most blanket assumptions allow for:
| District | Fineness | Gold content |
|---|---|---|
| Morelock Creek, AK | ~922 | 92.2% |
| Second locality, AK | 897 avg, 16 assays | 89.7% |
| Koyukuk–Chandalar, AK | 893 avg, 46 localities | 89.3% |
| Fourth of July Creek, AK | 892 avg, 22 assays | 89.2% |
| Moran Dome, AK | 835 | 83.5% |
| Fortymile River region, AK | 620–927 range | 62–92.7% |
District figures, not lot guarantees. Fineness describes the metal alloy only — adhering quartz, clay or iron staining reduces the effective purity of an uncleaned lot further.
| Region | Typical gold content |
|---|---|
| Alaska | 82–93% |
| Yukon | 80–92% |
| British Columbia | 80–90% |
| California | 85–94% |
| Arizona | 78–90% |
| Nevada | 80–92% |
| Oregon or Idaho | 80–92% |
| Montana or Colorado | 80–92% |
| Georgia or the Carolinas | 80–92% |
| Australia | 90–96% |
These are the bands our calculator uses when a seller does not know their own purity.
Two things drive it. The first is the source: the lode a placer deposit eroded from had its own gold-to-silver ratio, and that carries downstream.
The second is distance travelled. As gold moves through a drainage, silver leaches preferentially out of the outer surface of each grain. Gold that has travelled far tends to assay higher than gold close to its source — and it develops a distinctly gold-rich rind.
That rind is why surface testing can mislead. XRF reads the outside, and the outside of a placer grain is purer than its interior.
This matters practically. A buyer using XRF alone may see a high surface reading, then apply a discount “for refining loss” that quietly assumes a lower bulk figure. The seller never sees which number was used. The defence is simple: ask for the tested figure in writing, on the offer, next to the weight and the rate.
Why the purity figure changes what “percent of spot” means →
Fineness is parts of gold per thousand. Gold at 890 fine is 89% gold, with the balance mostly silver. Placer gold commonly runs 700 to 950 fine, and the figure depends on the deposit rather than on the size of the pieces.
No. Natural placer gold is an alloy, almost always with silver. Typical placer runs the equivalent of about 18k to 22k. Anyone describing raw placer as 24k is either mistaken or rounding in their own favour.
Only with care. XRF reads the surface, and placer gold is often surface-enriched — silver leaches out of the outer layer during transport, leaving a gold-rich rind. That makes XRF read higher than the true bulk composition, which cuts against the seller when a buyer prices on assumed loss instead.
Have it tested by the buyer as part of intake, and insist the figure appears in your written offer. Formal fire assay is the most accurate method but it is destructive and only economic on larger lots.
Because it reflects the original source rock and how far the gold has travelled. Gold loses silver from its surface as it moves downstream, so fineness often rises with distance from the lode.
We test every lot on camera and put the figure in your written offer.
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