Calling all geoscientists!

One of our most beautiful Paesina Stone images has made it onto the front cover Geoscientist, the magazine of the UK’s Geological Society, with a selection of other images featured inside and introduced as follows: ‘Most geologists will remember the first timethey gazed down a microscope at a thin section and marvelled at nature’s hidden display of colour and texture. However, three years of undergraduate petrology, with its classification schemes and examinations, is bound to install a certain level of professional detachment towards the more aesthetic aspects of rocks and minerals.

The fact that rocks are studied for practical reasons, not just because they are nice to look at close-up, means that most people outside the profession have absolutely no idea of their hidden beauty. It sometimes takes someone from outside one’s own discipline to point out the obvious - seen close-up rocks and minerals, even those common ones like quartz and tourmaline that working geologist often take for granted, can be shockingly beautiful.’ Indeed they are, and I’m looking forward to seeing what delights await in two more batches from The Netherlands and another from my favourite US site, ‘Great Slabs’.

Dendrites from Germany

We’re planning to launch a collection of ‘images that look like plants but aren’t’, and this beautiful dendritic stone will certainly be amongst them. It arrived last week with several others from a German website – http://www.topgeo.de/ – and originates, like so many on the market, from the famous Solnhofen limestone, a fossil-rich Jurassic formation that lies between Nuremberg and Munich in Bavaria.
The plant-like branching patterns form through a process known as ‘Diffusion Limited Aggregation’: molecules of water-borne manganese move about randomly, and when they bump into each other, stick together. Repeated billions of times, various types of dendritic (‘leaf-like’, from the Greek) patterns emerge. These are amongst the most universal patterns in nature, at every scale from blood vessels to continental river drainage systems. There’s a book about them due out in September by the excellent science-writer, Philip Ball, the last of a trilogy based on his earlier book ‘The Self-made Tapestry’ – I’ve got that and the two that have already been published, ‘Shapes’ and ‘Flows’, and 'Branches' is a snip as a pre-publication buy on Amazon!

Dutch delights

I’ve just bought a selection of new agates from http://www.rayer-minerals.com/, the site of a lifelong Dutch collector, Henk Rayer. He has, he tells me, ‘a basement full of rocks’, including many from European countries – Germany, Hungary, The Netherlands – which are scarcely represented amongst the Formations images. One of his specialities, still well represented on the site, used to be drawings of clowns dressed in agate costumes – perhaps I should try to interest the next touring circus to come to Cardiff in some digitally printed fabric!
Both the images above come from agates found in a gravel pit at Arcen in The Netherlands. The brilliant red, hematite-dappled one is a greatly enlarged passage a few millimetres across on the original specimen, while the other must pack more colour changes into a few centimetres than any almost any agate I’ve scanned: I have a feeling it’s going to find its way onto silk at the earliest opportunity.
More than happy with the quality of Henk’s materials I’ve ordered some unique materials from him – a set of eight large cabochons commissioned from a Russian polisher using very rare agate from Kazakhstan. Needless to say, I’ll be posting some images from them at the earliest opportunity.

A world in a grain of sand

It was great to see a presentation of agate images from the website on http://geology.com/ this week and while browsing the home page I noticed a book I hadn’t come across before. Entitled A Grain of Sand it features extraordinary images by the author, Dr Gary Greenberg, taken with a 3D light microscope he developed and patented – you can find out more at his website http://www.sandgrains.com/.
It has been estimated that there are 48,000 billion billion grains of sand on earth and, true to the maxim that Nature never repeats herself, no two are exactly alike. But just how unalike is the real revelation of the book. Sand grains vary according to the rock they are derived from and the extent and nature of erosion they have undergone – the archetypal round grain of quartz is typically the product of several cycles of erosion over a billion years. Biological materials such as shells, diatoms and foraminifera also form a significant element in many sands, adding greatly to the microscopic variety of form and colour.
The centrepiece of the picture above looks like just the sort of thing I would like to scan. It’s made of chabazite, a glassy member of the zeolite family which, like many of the most beautiful minerals, are silica-based. The only snag is that this specimen is a mere 1/4mm across – not much larger than some of the specks of polishing powder I remove digitally as impurities! With Dr Greenberg’s book as stimulation, it is easy to join William Blake in imagining ‘a world in a grain of sand’.

Laguna agate

Most of the agate images on the website are made from Brazilian material. Recently, however, I decided to venture into the more expensive world of collector-quality specimens, amongst which Mexican agates loom large. Most come from Chihuahua, the largest of Mexico’s thirty-one states and reputedly home of the eponymous, diminutive breed of dog. Mexican agates were first documented in 1895, but it wasn’t until some fifty years later that a few American collectors, travelling a newly constructed highway, found small agate nodules close to the road. They are now commercially mined and prized by collectors and jewellery makers worldwide.
With the exception of the celebrated Crazy Lace Agate, which is featured on the cover of the Formations book that is for sale on the website and forms in cracks of an older Cretaceous limestone, Mexican agates are found in volcanic rocks from 38 to 44 million years old. Each variety is named after a nearby ranch, hacienda, or – like the Laguna agate shown here – a railway station. Laguna agates are famed for their fine colour banding and the exquisitely delicate detail shown above is an enlargement of an area only 1cm (3/8”) wide. It was bought from the website Beautiful Agates and happily, given its tiny size, required minimal ‘cleaning’.