A vivid blue powdery mineral was bought from a roadside stall in Morocco by Anna Grayson whilst on a fieldtrip. Subsequently it was brought to The Natural History Museum for identification and has since been confirmed by the Museum's Mineralogy Department as being new to science.
Anna Grayson is herself a geologist and has written geological books and programmes, but even she could not identify the mineral. After initial tests at the Museum using X-ray diffraction it became clear that the mineral had never before been described and was new to science. Led by Dr Gordon Cressey, a team of scientists has been performing various tests to discover what its structure and chemistry actually are.
Dr Gordon Cressey explained; "About 40 new minerals are being discovered and described world-wide each year, but these are usually so tiny in amount that they can hardly be seen with the naked eye. This new mineral is so unusual because the specimen is very large and because it is the most strikingly blue mineral ever discovered."
Anna Grayson said; "I'm thrilled to bits. Every stone has a story and this is a remarkable one. The fact that this mineral is new to science was discovered during National Science Week when I was presenting a BBC Radio 5 Live programme from the Museum demonstrates that National Science Week can be an opportunity for some real scientific discoveries to be made."
Seen under the microscope in light that has passed through a polarising filter - like polaroid sunglasses - the mineral has the fascinating property of displaying a kaleidoscope of colour; depending on the direction that light passes through the crystal, it changes colour from colourless to bright blue to bright purple. Viewed under the electron microscope, the mineral is actually made up of millions of crystals that are fibrous on submicroscopic scale - like asbestos.
Each crystal fibre is less than one tenthousandth of a millimetre across - this makes them very difficult to investigate by conventional means; the full investigation of this mineral may therefore take many years to complete.
The chemistry has been investigated by firing a beam of electrons into these tiny crystals which energises the atoms in them to give out X-rays. These X-rays have different energies depending on the types of atoms that make up the crystals.
So far, the main atomic elements detected by this method are silicon, aluminium, calcium, magnesium, iron and oxygen. The way in which these atoms are grouped and arranged in the crystal is being investigated by firing X-rays of a specific wavelength at a powdered sample of the blue crystals. The X-rays are diffracted by the rows of atoms in the crystal structure. The distances between the individual atoms in the crystal architecture can be calculated from the angles at which the diffracted X-rays emerge from the powdered sample.
From the growing knowledge of the structure and chemistry of this new mineral, scientists at the Museum are now beginning to understand the possible reason for its intense blue colour. It seems likely that iron atoms are present with different electronic structures, enabling an electron to 'hop' between two neighbouring iron atoms as energy is absorbed from parts of the spectrum of white light. Yellow, green and red light are the right energy to energise this 'hopping' process and these are absorbed leaving the blue light component of white light to pass unabsorbed through the crystal.
Dr Gordon Cressey said: "By studying minerals we gain valuable insights into the range of material properties engineered by nature. In such investigations we are taking lessons from nature. If we want to devise new materials, chemicals and crystals for useful purposes, then we should first look at what nature has managed to do; nature has had a lot longer to experiment than we will ever have.
"Once we begin to understand details of the immense range of treasures produced by nature, we can explore ways to modify the design of particular man-made crystals and materials to make them even more useful for specific applications. Nature still has surprises waiting to be discovered and these may prove useful lessons for future technological developments."
During this year's National Science Week - Friday 15 March to Friday 22 March - mineralogists at The Natural History Museum will be announcing their up-to-the-minute findings on the new mineral. This is a real example of how a new discovery emerges from the coming together of scientific curiosity, expertise and modern sophisticated technology. - ENDS -
For further information please contact the Press Office on 0171 938 9388.
Ref: 17/0703/96/GD
Issued: March 1996
