Is there Gold in my Cranborne Chase Stater?

Durotrigan “Cranborne Chase” (ABC 2157; VA 1235-1) staters start in a high silver/low gold alloy known as “white gold”. A question that comes up regularly is if you can tell how much gold is in a Cranborne Chase stater just by its weight? This is sometimes asked by sellers who are trying to extract a bit more value from what’s nominally a silver coin, and by buyers who are wondering if it is worth paying a premium for the potential gold content.

Analysis

The following chart shows the percentage of gold in a selection of Cranborne Chase staters plotted against their weights.

The data shows a general trend, starting somewhere between 4.6 and 4.9 g, where the gold content increases with weight, albeit within a large range. There are three outlier coins (circled) that break what would otherwise have been a linear relationship between weight and gold content.

The ranges for 0.1 g bins (upper > coin >= lower) are:

Empty cells represent 0%. Note that the data available is limited and there’s no guarantee that all coins will fall within these ranges. For example, the table suggests that coins weighing 5.9 to 6.0 g have a fixed gold content of 17%. This is unlikely to be correct. 

Can the Outliers be Explained?

The following coins are outliers in the graph above:

The 6.06 g coin was found in the 1957 Catillon hoard which also contained a silver Chute stater (although the photographs suggest it is actually gold). It’s tempting to argue that the hoard contained “defective” coins that were being removed from circulation, and therefore we can ignore this outlier, but that’s probably an unsafe assumption to make and even if it were true, equally “defective” coins could remain in Britain and be the target of this question.

The two coins from the Corfe Common hoard don’t appear to be anomalous in any way, and the 4.92 g coin with 13% gold (BM 1984,1107.7) is struck from the same dies as BM 1984,1107.13 which is 6.05 g and 10% gold.

There’s no reason to ignore any of these outlier coins. 

What About Similar Staters?

There are three other types of staters which are similar enough to Cranborne Chase staters that people may ask the same question of them: Spread Tail (ABC 2160; VA 1238), Badbury Rings (ABC 2163; VA 1246), and British Af Lepe (DK 296) staters.

There is no metallurgy information available for the Spread Tail staters, and the only data for the Badbury Rings type has a weight of 4.58 g which is below the level where gold was a possibility. 

The British Af “Lepe” staters are visually similar to the Cranborne Chase staters and are frequently confused with them. They start in gold and end in silver, and therefore go through a “white gold” phase as well. There is insufficient data to fully understand the metallurgy of these coins, but one coin (BM 1984,1107.26) weighs 4.9 g and has 8.7% gold which is similar to the Cranborne Chase “outlier” (BM 1984,1107.7) which weighs 4.92 g and has 13% gold. As these staters started in gold (an earlier one has been measured to have 55% gold) it should be expected that they have gold in them even at low weights. 

Conclusions

It probably doesn’t make sense to pay extra for a coin unless the gold is visible

Based on the data available, Cranborne Chase staters start having a measurable gold content at 4.9g, but the range of values is large and could be as low as 3% even in coins over 6 g.  With such a potentially low gold content it probably doesn’t make sense to pay extra for a coin unless the gold is visible.

Catalogue of Cranborne Chase Coins

If you are viewing this on a mobile phone then you might need to turn it to landscape mode. The last column is “Cu %”