Found a good example of quartz the other day. I have given it a clean under the tap etc. with a toothbrush but it still has some inclusions on the surface. Can anybody advise on suitable methods of removal. If i can get it clean it will look good on the mantlepiece

True inclusions are material occurring within bubbles in the quartz - in which case they are part of the specimen. I suspect you mean surface deposits - maybe iron oxides or wad (manganese oxides). Try dilute acid or strong caustic. Do not use abrasives.

If the acid makes the quartz itself fizz then you have calcite, not quartz!