Mineral identification at Amgueddfa Cymru Amanda Valentine & Jana Horak, 7 December 2009 The X-Ray diffraction machine at the Museum Passing of an X-ray beam through a rock sample from the source to the detector Quartz crystal Graphite Diamond Langite wroewolfeite One of the activities of the Geology Department at Amgueddfa Cymru is to document all the minerals known in Wales. Minerals can be identified visually, but for a more definitive confirmation a process known as X-ray diffraction analysis (XRD) is used. This technique allows natural minerals and man-made crystalline materials to be 'fingerprinted' and compared to a database of known samples. X-ray diffraction analysis Most minerals are crystalline, which means they are made up of a regular framework of atoms creating a unique 'crystal lattice'. When X-rays are passed through a mineral, the atoms cause the X-rays to be diffracted, or bent, into many directions. The resulting X-ray pattern can then be recorded to produce a 'fingerprint'. Because no two minerals have exactly the same arrangement of atoms, their 'fingerprints' (or lattices diffraction patterns) are unique. These patterns can therefore be used to identify the mineral. To analyse a mineral by XRD a small sample, usually ground into a powder, is bombarded with X-rays. The data is recorded as a graph, called a diffractogram, which is a convenient form for viewing the result. To identify the mineral, the result is compared with a database of patterns from thousands of known minerals. An X-ray pattern of quartz showing its unique pattern Identical looking minerals Visual identification is still important, as it is possible for two different mineral species to have the same chemical composition but look very different. For example, diamond and graphite (both pure carbon) have the same chemical composition, but are clearly different not only in appearance but also in hardness and crystal form. On the other hand, langite and wroewolfeite are two chemically identical copper minerals that both form blue needles and are consequently difficult to tell apart visually. But because they have different crystal structures and therefore produce different diffraction patterns, XRD provides a quick and reliable method for distinguishing between them. Some minerals don't have a regular crystal structure and therefore don't produce diffraction patterns. Known as 'Amorphous minerals', they cannot be identified by XRD. A diffractogram pattern of an amorphous sample with no identifiable peaks The application of XRD The technique is widely used in geology and also in a range of related disciplines. For example, it is used to identify minerals in artists' pigments and the composition of corrosion on archaeological artefacts. Conservators can then devise the appropriate treatment for museum specimens.
''Christmas is coming, the daffs are getting fat!?'' Chris Owen, 5 December 2009 Merry Christmas Bulb Buddies!So many of you have reported sightings of new shoots and it's not even Christmas yet! This week my shoots have appeared too, they are about 2cm tall -see my picture.This autumn is much warmer than last years. The average temperatures in Wales for October and November are almost 1.5 degrees warmer than they were in 2008. As a result, many daffodils have started growing already. Farmers from the Really welsh farm reported: "We too have lots of daffodil shoots coming through, the warm, wet weather should mean that our daffodils will be ready for the shops in the spring. The flowers may open a few weeks earlier than last year".If we get a frosty spring next year, this could damage some of the daffodils that have started growing. These Daffodils are very tough though - so they still should produce beautiful flowers. It will be interesting to see if the early shoots grow into early flowers. Watch this space...Thanks to all of you young scientists who are keeping such accurate weather records - they are really useful to help us understand what is going on with our seasons and nature. Please let us know here if you see any other plants growing early.Don't forget! This week hundreds of scientists and world leaders are getting together in Copenhagen to make a deal to help save the planet. It's being called one of the most important meetings in the world! See newsround for the latest and let me know what you think.Next week, is the last week for recording before Christmas - then you all can enjoy your holidays.Have a fantastic Christmas!Professor Plant
Art Cart - 5,12,19,21,22,23 December Chris Owen, 4 December 2009 This Saturday on the art cart we will be getting ready for Christmas by making wrapping paper, tags and decorations. There will also be some Christmas colouring sheets for little ones.As usual, the art cart will be in Oriel 1, St Fagans: National History Museum between 11-1 and 2-4.
Tree O'Clock! Chris Owen, 23 November 2009 With the arrival of strong winds and heavy rain over the last week or so I am preparing myself for the end of autumn and the imminent arrival of winter. It’s a shame to say goodbye to the mild autumn we’ve been having, I’m going to miss the many warm hues on display amongst the trees of St Fagans. But farewell it must be, as the sudden blast of heavy weather has stripped the trees of their finery and left the leaves gathering in thick layers upon the ground.Despite this brutal de-glamorisation, trees are to be the focus of my activities over the next few weeks as we celebrate National Tree Week. During the last weekend of November we will be looking at the many different types of tree at St Fagans and finding out the best way to identify them by looking at leaf, seed, bark and bud. The RSPB will also be with us, running activities that highlight the importance of trees to our native birds. Incidentally the bird cam at St Fagans is pretty busy at the moment and you can follow the action via my twitter pageAnd if you’ve ever wanted to be a world record holder why not join us on Saturday the 5th of December for Tree O’Clock? We will be attempting to set a new Guinness world record for planting the most trees in one hour in collaboration with BBC Breathing Places. And if you enjoy getting into the festive spirit why not stay on and make sustainable Christmas decorations from the Hedgerow at T? Gwyrdd?Sustainable Christmas will also be the theme of my activities at the ever popular Christmas nights on the 9th, 10th and 11th of December. Be sure to bring a torch and warm clothes as it can get pretty cold here at night!
Shoots already? Danielle Cowell, 19 November 2009 Pupils from Oakfield Primary School asked: 'When will the bulbs sprout?'Normally, I would say 'nothing much will happen until after Christmas', but some bulbs have already decided to pop up through the soil!Pupils from Pentrepoeth Junior School reported: 'We were very surprised to find the shoots and we have now noticed a few more in our flowerbeds. I am attaching a photo for you to see.'From studying the photograph, although I can't be 100% sure, they certainly look like daffodil shoots. Compare my photograph from last year - what do you think?Please leave a comment if you see any early shoots or email any photographs to scan@nmgw.ac.ukMany Thanks, Professor Plant
