Fossicking is a fabulous word that I first discovered in Peter Carey’s book Oscar and Lucinda. It describes the glassmaker rootling around in the bucket to find “Prince Rupert’s drops” which form accidentally when molten glass falls into a bucket of cold water during the glass blowing process.

..and here is the wonderful piece of writing by Peter Carey

You need not ask me who is Prince Rupert or what is a batavique because I do not know. I have, though, right here beside me as I write (I hold it in the palm of my left hand while the right hand moves to and fro across the page) a prince Rupert drop – a solid teardrop of glass no more than two inches from head to tail. And do not worry that this oddity, this rarity, was the basis for De La Bastie’s technique for toughening glass, or that it led to the invention of safety glass – these are practical matters and shed no light on the incredible attractiveness of the drop itself which you will understand faster if you take a fourteen-pound sledgehammer and try to smash it on the forge. You cannot.

This is glass of the most phenomenal strength and would seem, for a moment, to be the fabled unbreakable glass described by the alchemical author of Mappae Clavicula.

And yet if you put down your hammer and take down your pliers instead – I say “if”; I am not recommending it – you will soon see that this is not the fabled glass stone of the alchemists, but something almost as magical. For although it is strong enough to withstand the sledgehammer, the tail can be nipped with a pair of blunt nosed pliers. It takes a little effort. And once it is done it is as if you have taken out the keystone, removed the linchpin, kicked out the foundations. The whole thing explodes. And where, a moment before, you had unbreakable glass, now you have grains of glass in every corner of the workshop – in your eyes if you are not careful – and what is left in your hand you can crumble – it feels like sugar – without danger.

It is not unusual to see a glass blower or a gatherer scrabbling around in a kibble, arm deep in the oily water, sorting through the little gobs of cast-off cullet, fossicking for Prince Rupert’s drops. The drops are made by accident, when a tear of molten glass falls a certain distance and is cooled rapidly.

You will find grown men in the glass business, blowers amongst them, who have handled molten metal all their life, and if you put a Prince Rupert’s drop before them, they are like children. I have this one here in my hands. If you were here beside me in the room, I would find it almost impossible not to demonstrate it to you, to take my pliers

and – in a second – destroy it.