Probably you could but you need to rely on some kind of electronic nose, these e-noses.  I don’t know how good our technology is at the moment with sniffing these things out with something that’s portable and cheap.  The benefit of combining a simple robot with a well trained Mongoose is that it’s very low-cost and it is quite disposable.  If you blow up a very expensive equipment obviously there’s a greater cost to that.

Chris: I don’t know, Helen, do you know this?

Helen: I don’t know actually, it’s a good question. I can only imagine they do. I can imagine that they can chew them, they’re quite bendy. They can probably chew their toenails. But we can find out. Anyone got any ideas?

Chris: If you have any clues, do get in touch.

We put this question to Ian Mercer:

Well, we were talking about volcanoes earlier. Now, if you think of a volcano after it erupted and all this black lava comes out and it starts cooling down then, as it cools, some of the gases start fizzing out. They form big bubbles and those bubbles gradually fill with more minerals as the water flows it cools the lava. These minerals line the side of what was the bubble and because the lava very often turns to a sort of soil and wears away you’re left with this hard mass which was the lining of the bubble. Some of those when they’re broken open you find that they’re lined with these beautiful crystals, quite often amethyst which is purple quartz.

We put this question to Ian Mercer:

Edinburgh actually is partly built on, or the castle is certainly built on, the remains of a volcano. Actually it’s a basalt volcano. Yes, you can get gems in basalt but if you search all the basalt around the world looking for gems you’ll only find gems in relatively few, relatively speaking. Before you try to seek permission to dig up Edinburgh I’d think about the geology first.

Chris: There’s probably better things to find in Edinburgh like whiskey, for example!

We put this question to Ian Mercer:

The short answer is yes, that is true.  Tanzanite is a really beautiful gemstone.  It’s a gem variety called zoisite which really occurs as a sort of powdery crust – greeny blue and brownish colours.  Certainly not gem quality.  That place in Tanzania is the only place in the world where quantities of gem quality zoisite form.

Chris: Chemically what is it?

Ian: It’s another of these silicates.  It’s a pretty complex silicate in fact.  We won’t go into the formula because it would take longer than a minute.  It’s an orthorhombic silicate.  One of its attributes is that it changes colour as you turn the stone around.  It’s what’s called dichroic.  It’s treated in order to improve that blue colour as with most gem stones.

We put this question to Ian Mercer:

This is an interesting stone.  This forms at very high pressure.  This isn’t a volcanic stone, this is a gemstone that forms as a mineral in rocks that are squeezed in between something.  This is a stone which is intensely dichroic.  It changes colour completely as you turn it round.

Chris: Where do you find it?Ian: That comes form all sorts of places like Norway and Africa.  Anywhere where deep-seated rocks are pushed up towards the surface.