Calennig

On the 30th and 31st of December between 11am and 12.30pm we will be making Calennig gifts(like the one in the picture above!)

At 2pm there will also be a chance for you to sing with the Calennig gift you have created. It's going to be so much fun!

And if you are wondering what the apple on a stick is all about, here's what Trefor M. Owen has to say in his fantastic book 'Welsh Folk Customs':

'The giving of gifts on New Year's Day is an ancient custom once widely observed but more recently displaced by the growing importance of Christmas and Christmas presents. The collecting of calennig (New Year's gift)is a Welsh form of this custom.

[...]the collecting of calennig began early in the day and continued until noon. An account published in 1819 describes the custom in the following words: 'New Year is marked by all the children in the neighbourhood forming themselves in little groups and carrying from house to house their congratulations and good wishes for the health and prosperity during the ensuing year, which are symbolized by each bearing in his hand an apple stuck full of corn, variously coloured and decorated with a sprig of some evergreen, three short skewers serve as supports to the apple when not held in the hand, and a fourth serves to hold it by without destroying its many coloured honours.''

Icy St Fagans

St Fagans:National History Museum has been closed today due to the poor weather conditions. I went out for a walk to take some photographs and it's very slippery but also so pretty!

Mineral identification at Amgueddfa Cymru

X-Ray diffraction machine

The X-Ray diffraction machine at the Museum

Passing of an X-ray beam through a rock sample from the source to the detector

Passing of an X-ray beam through a rock sample from the source to the detector

Quartz crystal

Quartz crystal

Graphite

Graphite

Diamond

Diamond

Langite

Langite

wroewolfeite

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

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

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!?''

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

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.