Tuesday, 15 March 2011


Here's another little object from my cabinet of curios - it's a piece of volcanic glass which I pulled out of the wall of a late 18th century grotto that I restored some years ago, then cut and polished to reveal it's true colour.

Most obsidian is black or a blackish-green, but this - as you can hopefully see - is a vivid deep blue which I have never seen before in a piece of volcanic glass. The blues and greens (I guess) must come from the copper or cobalt content of the ground that the molten lava flows over as the volcano erupts, and the natural glass is created by the silica sand fusing in the great heat.

This lump was most likely brought back from a Grand Tour of Italy and Greece that the grotto-builder embarked on sometime during the late 1700s, and is quite possibly from Vesuvius, which was a popular, smouldering destination at the time. There are many 18th century coins in existence, set in little lumps of set lava as mementos of their visits up the slopes of the volcano. It was fashionable to build grottoes to house private geological specimens to show to your friends, and even in 1790, only the very wealthy could afford to make them. The one I restored (at a cost of about £15,000) still has it's original bill for labour, and that bill was for about £40,000 - in 1790!

I didn't really steal this lump (honest) - it came from a pile of ordinary rubble set behind the face of the wall, and it wasn't until I was about to throw it away that I realised that it was not ordinary rock, so I polished it up to see how it looked.

A beautiful spin-off from another natural disaster.


  1. It's lovely. How big is it? Paper-weight size? Piece of jewellery for Her Indoors size?

  2. Funny you should say that, Mise - if you look closely, you will see an oval shape marked onto the face of it. I considered making a bangle for H.I.'s very slender wrist, but decided that the piece would never survive the cutting, due to inherent, natural fractures. Its about 4 inches long.

  3. I think that you should have a separate cabinet of curios blog, Tom. A beautiful piece of obsidian, like an aerial photograph or seascape.

  4. It is just lovely ...
    Obsidian's history, being the remnant of still-forming continents, is fascinating. I did a unit at a New Zealnd uni about how the trading movements of obsidian that supported historical theories about Pacific people's origins.
    In archaeology we learnt that obsidian becomes more valuable the further it goes from its source.
    A statement on globalisation then, when I was selling beautifully knapped obsidian arrowheads that I'd bought in NZ and came from Mexico, at the Denmark markets in Western Australia, for ten bucks apiece.

  5. I wonder why the one side is 'dead straight'?

    Yup that'd go in my cabinet too. Is it just folk in 'The Arts' who collect such things. I can't bare to throw out anything that's attractive or unusual....that's why chez nous is such a bloody mess!

  6. I think you should do a blog showcasing all of your curios...

    we could all add to it blog wise.....

    I could add a small lump of concrete....( picked up from the exercise yard in Alcatraz!

  7. Stones really interest me Tom. I brought back a bit of lava off Etna - actually it looks just like a bit of coke! But I often think that there is such beauty beneath our feet if only we take the time to look carefully. I have a friend who is very good at finding bits of garnet and bits of jet on our beaches. I never seem to see them.

  8. Ok - thanks all, maybe I'll do a separate 'Cabinet' blog.

    One side is 'dead straight' because I cut it dead straight, Cro - keep up - DERR!

    I almost bought an obsidian arrow head recently, Sarah, but the trouble is that you don't know if they are made in China these days, unless you find it on the ground yourself.