Gold has always been in something of a twilight zone in that regard. It's no longer officially considered money. So it's usually regarded as just a commodity, like copper, lead, or zinc, for these purposes. The one-ounce Canadian Maple Leaf and US Eagle both say they're worth $50 of currency.

But I've had some disturbing experiences over the past couple of years crossing borders with coins. Of course, crossing any national border is potentially disturbing at any time. You might find yourself interrogated, strip searched, or detained for any reason or no reason. But I suspect what happened to me crossing a few borders in recent times could be a straw in the wind.

I've gradually accumulated about a dozen one-ounce silver rounds in my briefcase, some souvenirs issued by mining companies, plus others from Canada, Australia, China, and the US. But when I left Chile not long ago, the person monitoring the X-ray machine stopped me and insisted I take them out and show them to her.