Oak Island archaeology update: Gun stones and rose gold

So far, season 9 of Curse of Oak Island (COOI) has focused on a couple of finds: Gold, sometimes described as flakes, that seems to show up as microscopic grains, or inclusions in two metallic objects, and small stone spheres, identified on the show as gun stones.

According to the COOI team, the gold flakes help to confirm that there is buried treasure on the island, and the gun stones, described as being made of gabbro and basalt, suggest an exotic origin, on some volcanic island somewhere to the south.

In fact, neither the gun stones nor the rose gold are surprising finds on Oak Island, and neither help support the idea that there is a buried treasure, Templar or otherwise on the island.

Rose Gold

There is actually lots of gold in the Oak Island region, and it isn’t surprising to find it on the island in the form of microscopic grains in core samples, and in groundwater. The island sits at the southern edge of the Goldenville geological formation, and at the mouth of the Gold River, in which panning for gold was practiced historically.

The Lacey Gold Mine operated in the area from the 1860s until the Second World War. The Lacey Gold Mine Campground is now located a 15 minute drive from the Island, according to Google Maps.

According to this Nova Scotia government document, grain in the disseminated gold deposits of the region “are 0.5 µm to 2 mm in diameter, but most are < 100 µm.” That is consistent with the grains shown under the electron microscope on the show, which seemed to be a few microns across.

Contrary to what has been claimed by the COOI team, and contrary to what you can read on many jewelry oriented web sites, copper-gold alloys definitely do occur in nature. One of them is commonly called tetra-auricupride (Au₃Cu), and is consistently composed of 75% gold, and 25% copper, which matches the gold grains analyzed on the show. For a handy table of naturally occurring gold-copper alloys, see page 575 of this article in the Canadian Mineralogist (Knipe and Fleet, 1997).

Deposits of natural rose gold that are commercially viable are fairly rare, but that doesn’t mean it doesn’t exist elsewhere in smaller quantities. In fact, there is even a nearby deposit in Northern Nova Scotia which is apparently a good candidate for containing commercially viable concentrations of tetra-auricupride.

The first order of business for the COOI team, then should be to get core samples on the island and elsewhere in the area, to see if the same Au₃Cu grains show up, and if so, with what frequency. The obvious question, as always, is whether these grains are a surprising find on the island or not. Until we know that, it is premature to consider them evidence of treasure.

Gun Stones

The so-called gun stones are of interest to the COOI team for two main reasons: First, the team suggest that they help date activity at the site. Since gun stones post-date the use of fire arms, but predate the use of metal ammunition, they would be an indicator of very early European presence. Second, they have been identified as being made of basalt and gabbro, which according to the team, indicates an exotic and faraway origin.

Basalts and Gabbros are, of course, widely available in Northeastern North America in general, and in Nova Scotia specifically. While basalts and gabbros are currently being produced on volcanic islands far away from Oak Island, they were being produced locally millions of years ago. The volcanos are long gone from Nova Scotia, but the basalts and gabbros they produced are still there. See here for just one example of a Nova Scotia locality rich in both.

The second question, that of the dating of the gun stones, which, as an archaeologist, I would call pecked stone spheroids, is much more interesting. These spheroids are present in the archaeological record at various places and times, from very early examples in Africa, to more recent ones in Europe, the Americas, and the Pacific, among others.

There isn’t a lot of work on them. I found this recent MA thesis from Emily Crump (2020) who did a comprehensive survey of spheroids in a large region of the American West, from a period dating to between 1000 and 2000 years ago. They are the same size, shape, and apparent weight as the Oak Island spheroids. I know they also occur on some archaeological sites in the northeast.

It is quite likely that these “gun stones”, are in fact indigenous artefacts. They could be more recent, around 500 years old or so, but they could also be several thousand years old. With the recent and unsurprising find of indigenous pottery on the island, I suspect Laird might be looking at the spheroids very closely. In any case, the spheroids are not unexpected, not surprising, and definitely not evidence of treasure on Oak Island.

As usual, where there are complex and unlikely, and really interesting explanations for the finds on Oak Island, there are also simpler and more likely ones that need to be ruled out. The simple and likely ones are just as interesting to me.

References:

Crump, Emily, “Spherical Objects Among the Fremont” (2020). Theses and Dissertations. 8399. https://scholarsarchive.byu.edu/etd/8399

Knipe SW and ME Fleet 1997. Gold-Copper alloy minerals from the Kerr Mine, Ontario. The Canadian Mineralogist 35:573-586.