In the dark ages and even after, it wasn't uncommon for coins to be halved or quartered, as a way of making "change". In fact, so many medieval coins have crosses with equal arms on the back that you wonder whether it was piety or convenience. All you had to do is snip along one of the arms!

Apart from that, coins are sometimes clipped in odd ways. For some period of Byzantine history most coins you see will look oddly five or six sided, as though counterfeiters had trimmed them to use the metal in striking fake coins. But apparently it was official policy to recall old coins, trim them down to reduced "modern" weights, and make more offiical lighter weight coins. Legal counterfeiting, in effect.

Then there are barbarouis imitatives, generally made in out of the way places where people have seen money from Persia, or Greece, or Rome, but almost none comes their way. They may make their own, copying better money they've seen. In general they tend to be cruder, lighter, and more irregular in shape.

A coin can be corroded too. One edge may be more seriously eated away, chemically, by the soil its in, leaving it looking as though it was only part of a coin. Then there are "bad strikes", where the coin comes right out of the die, crooked or lopsided. Skilled coiners avoid this... most of the time. But there are clinkers. Just so long as the weight is true, though, nobody cared. Oh, the supervisor might complain about sloppy workmen, because the emperor might complain to him about the official representation of his majesty looking shoddy.

But the people who passed coins back and forth only cared about the value in metal. The coin could be rolled up in a ball, but as long as it looked like silver and seemed the right weight in the hand, that was good enough. People can be uncannily sensitive to such things. With a little practise most people can sense a difference of weight of only a fraction of a gram in their hands with their eyes shut. Apparently, the slighter the weight, the more sensitive you can be. A difference of several grams in a kilogram is undetectable, of course, but a difference of a tenth of a gram between two objects weight one gram is quite noticeable. As for purity, you get the knack of looking at a coin, evaluating how its worn, and what it should look like depending on the percentage of silver. In fact, you can *taste* silver. It tastes nothing like nickel or steel.

So... bottom line. Maybe what you saw wasn't a chip from a coin afterall. It may have been deliberately divided up. Or it may be defective or damaged by time. Or it may even have been struck that way.