Hi John,

I have had quite a lot of success in using DIY tile cutting saws to cut rocks and glass sheet. Saw blades are available from about 25mm diameter upwards but they require a cutting speed of about 10,000 rpm to cut efficiently. The small ones are also fragile. You also need a good supply of water to act as a lubricant and to wash the cuttings away. A pump up garden spray might be a simple way of providing this. In choosing a saw the speed is the main factor. Small hand held saws are usually called trim saws in the UK. You can hire them from the big tool hire companies. You can also hire the professional diamond saws but these usually have a blade of about 300mm diameter and a petrol engine. If you only need to cut small sample a 50mm diameter wheel powered by an electric drill might work but drills often run at much lower speeds. You would have to try it but 50mm discs only cost a couple of pounds and you may well already have a drill. Water is still required of course.

Can I finally endorse Alan's concern. I have seen the result of sampling using straight cut saws in the Kola region of Russia. They leave one hell of a mess, far worse than core drilling. This is mainly due to you having to cut at least one saw blade diameter longer than the cut you wish to make due to the circular profile of the blade. This suggests using as small a diameter blade as possible. With care and careful choice of the sampling site you should still be able to get away with it.

Good luck,

Bernard