SAND ....a world on its own. By Carla Lagendijk, the Netherlands.

Images by Loes Modderman, the Netherlands.

 
 

Microscopy, whether we use it for our job or for our hobby, opens up a world of unknown beauty, especially as there are hundreds of things in our world which, the tinier they are, the more they astonish us while examining them with the aid of a microscope.
But……….sand??

A fair number of people will never think about sand, as it is a very ordinary material.
It belongs to the daily things of life; we walk over it on our strolls, we use it as a basic material for our houses or roads and some artists use it to build beautiful sand castles or even make sand paintings.
Sometimes we like it, sometimes we really hate it.
Most people do not wonder about the origin of sand.
That many, many thousands of years have gone by before rocky material finally turns into sand or clay. That even the sand, eroded from sandstone rocks, is actually sand deposited as a beach, dune or desert millions of years ago, turned into sandstone cliffs and eventually eroded for the second time.
 

But…who will consider to look at sandgrains under a microscope?

Well……me! And luckily I am not the only one.
I collect sand samples for almost 6 years now and, as a result of my hobby, I also try to get more knowledge of the geology and mineralogy than the little bit I already know.
 

It all began on a lovely beach on the north-eastern coast of Crete……………..

Used to our Dutch beaches, nice but with no trees at all, this beach with a lot of palm trees took my fancy so much that I collected a sand sample (and a piece of a palm tree, yes, that is me!) as a souvenir.
The second sample was an orange-coloured desert sand from a rather high sand dune in the south of Morocco, where we (my partner Rens and myself), after a hot and breathtaking climb upwards, finally sat down to admire the very special view over a part of the Sahara and to listen…to the incredible silence, until we had to hurry down as an awful desert storm suddenly came on. A slightly painful experience for our bare legs, which almost got sandblasted.
More sand samples followed and they all looked very different; the texture, the grain size as well as their colour. They felt different to the touch as well.
As the microscope was at hand a new fascination was soon born!

Again and again it is amazing! A whole pebble beach in a few mm², sometimes with grains as sharp as glass, sometimes shiny and well-rounded. Sometimes a multi-coloured, sometimes a completely organic material consisting of tiny shells or shell fragments.

Spain: Estepona beach

I noticed the differences in the various kinds of sand, e.g. from beaches, rivers, dunes, mountains, deserts and also from sandpits or quarries.
 

But first; when is this material actually called "sand"?

We call it sand when the grains have diameters between 2mm and 0,05 mm.
When the size of the grains is above 2mm it is gravel, below 0,05 mm it is called silt or clay.
We usually say; when you can still see the grain with the naked eye it is a sand grain.
 

And what about the composition and source of the sand?

Sometimes it is a deposit, completely or largely consisting of organic material as shells, skeletal fragments from sponges, nicely coloured needles from urchins or other marine organisms or erosion material from coral reefs.

Mostly this kind of sand is of local origin, unless very strong ocean currents transport the material way-out of the original spot, which can happen.

Corsica: Tizzano beach

Some more or less organic sand can contain really fantastic-looking, tiny "look-through" shells, not detectable with the bare eye and astonishingly perfect, even in samples from rather crowded beaches. You would almost think it impossible with all those feet going over it!

Vietnam : Da Nang beach.

More often however the source of the sand is way up in the mountains and is being transported by rivers, sometimes for thousands of kilometers.
You will find the sand or rock particles from the source of the river much different from the ones miles and miles further on along the riverbanks, as they are subject to abrasion and impact with other grains along the way down to beach or lake.
Most of the nice looking particles you find in this sand coming directly from the source, slowly turn into silt as they are too soft to withstand all the bumping on their long journey to their final resting place.
In the meantime, other rivers will add different materials and so the composition gradually changes.
Out of my samples from the river Rhine you will immediately recognise the sand sample which came not very far from its source area in Switzerland, whereas the Rhine material 400 km further on carries a lot of fairly rounded quartz and contains some different minerals from the areas in Germany where the river forces its way through.

Switzerland : Valendas - Vorder Rhine
 

Germany : river Rhine at Iffezheim

Beach sands usually have rather smooth grains, due to the constant wash of the waves and the grains are generally quite clear.
Dune sands on the contrary are being sandblasted by the wind and so, after a long time, the grains get a round and dull appearance, which can also be the case with the grains of desert sands, when they have been blown away for miles and miles.
Oxygen and silicon are the most frequently occurring elements in our earth's crust, thus quartz is very abundant in our rocks. You will often find an overdose of quartz in most of the sands as well. Quartz is also comparatively hard. No wonder it can survive long journeys, where other minerals can not.
Nevertheless it is light in weight and thus easily blown away by the wind to form dunes.
The darker the sand, the heavier. The more heavy minerals you find in your sample, the more interesting it will be of course.
Last year, walking around (nose-downwards) on a beach on the island of Corfu, I discovered a dark spot between the large pebbles. Everybody would think it was dirt, oil or whatever, but it was caused by heavy minerals (magnetite, ilmenite, garnet) sorted out by the seawaves and
beautiful under the microscope!

In Holland we find this "heavy mineral" sand in special places in the northern part of the country and on the islands Texel and Ameland. Strong NW winds deposit these grains near the dunes, though it is not easy to find, as it is usually covered by quartz and other lighter material.

Netherlands : island Texel

So, when you notice dark or darker patches in the sand and you are interested in the contents, just scoop them up carefully. It is more often deposited as a thin layer, so in this case, do not use a shovel but an old spoon instead or something flat anyway! (When it is oil, you will notice it soon enough!)
It may contain these beautiful minerals, e.g. garnet (pinkish red), ilmenite (metal black) or magnetite, which you can detect with a magnet.
You will very much enjoy your jewelbox!!
 
 

Greece: island Corfu/ Limni Korission beach

Talking about dark sands: Let us not forget the dark volcanic sands!
We do not like to sit on this kind of sand or walk on it with our bare feet as it soon gets too hot for our liking, but have a close look at it! Now you know why it does not feel pretty and it gets very hot under your feet!
It is almost completely composed out of glassy material.
It may consist of lava grains (lava is the cooled-down fluid basalt which has streamed out of a crater) and pumice (when the magma cools down in a foamy way). They have a rough appearance as we all know, one is black or brown, the other is white, but look at it under the microscope! Glassy indeed.
Often you will find nice green olivine (sometimes the elongated crystals) and obsidian, black or brownish (with no shape at all, but very sharp) in the black sand.
The Green Sand Beach in the south of the island of Hawaii (Big Island) contains just this green, well-rounded olivine.
Obsidian is the well known massif, volcanic glass, which develops when magma cools down very quickly without having time to crystallize.

Island: Santorini - Red Beach

 Hawaii: Green Sand Beach.

Beside these sands you can also collect sand samples for their colours of course.
Wonderful colours you may find or get from Australia's Red Heart (e.g. Ayers Rock and surroundings) or the sands from the beautifully shaped sandstone formations in Utah, Arizona or Colorado, the Namibian desert sands or sands derived from the coloured rocks in the old town of Petra (Jordan); though under a microscope they may be somewhat disappointing.

Sandpits are interesting as well, but often you need permission to enter. In some sandpits (e.g. in Belgium) you find fossil sea sand and it is a game for some people to look for small sharks teeth in a special layer, but sand freaks can look for tiny fossils, called nummulites, hardly visible by the naked eye and a special item to have in the collection.

Belgium: Balegem sandpit: nummulites

Sometimes sandpits are locations where they dig for the so-called ochre sands, out of which the pigment is extracted for industrial purposes (France, Lubéron), although exploitation has almost come to an end nowadays. The old quarries are more or less open for visitors in summer. These sands display a wide range of colours, because of the ferruginous minerals. Even a light purple colour.
As my own country Holland is very much of a "sand country" (and clay of course) we have plenty of sandpits too with fine as well as coarse nicely-coloured sands, only here the exploitation is for the fabrication of building materials and road constructions.
 

I've just remembered an anecdote:

One day I visited, together with Alie, one of my girlfriends, a rather large sandpit in the north- eastern part of Holland near Emmen. When we explained why we would like to gather some sand samples, we got permission to look around and take what we wanted.
Well, this was easily said, but the pit looked more like a lake with steep, sandy hillsides than a sandpit.
Finally a fellow, working on the dredging-machine came to get us in a terribly rusty, tiny 2-person sort of boat, more like a biscuit-tin with an even tinier motor. We got in, crossed the lake to reach the sand, where (after he had explained to us how the engine worked), he got off to scoop many different coloured sands for us.
Suddenly it became rather exciting as the biscuit-tin started to drift off to the middle of the lake, leaving him at the side, shouting louder and louder what we had to do. Because of the noise that stupid little engine made and the distance getting longer and longer, we had to scream louder and louder as well. With the sweat in our hands we finally got the boat, zigzagging over the water, back in the right direction and he got in with wet feet but with bags full of sand. I really thought he would have to swim.
With 8 bags of nicely-coloured sand we were satisfied, he turned the boat but … halfway across the lake, the engine decided to fail twice.
At first I thought our friend could make a joke, well, with 2 women in your boat, but no, he was too serious a fellow. Then we feared the worse, but after all, the little bit of petrol proved to be sufficient to bring us ashore.
We uttered a sigh of relief, but after all we enjoyed our small adventure very much.
That is what can happen on the search for sand grains!
 

About my collection:

It consists out of about 4200 samples at the moment and I collect sands from all over the world.
How to collect is a personal matter, it also depends on the accomodation you have.
Keeping this in mind (you never know what the future will bring) I use small glass bottles.
Some people use laboratory vials, which are available in different sizes, others store it in photo/film canisters or in small boxes.
In the living room I have a showcase with 1400 samples of all kinds of sands and colours from all over the world. Some visitors think we use a lot of medicines!
As one cannot travel all the time, we are always interested in getting or exchanging sand samples with others. Family and friends sometimes bring sand in plastic bags from their holiday or business trip location, which is very nice and of great help. (On the label give the place of the find as clearly as possible).
We have just returned from Cyprus with 25 kg of sand!
It's good we do not go on holiday every month for I am afraid my arms would look like Popeye's arms in no time and I hate spinach.

By now you will either think this is a nice, interesting hobby or you will have fallen asleep.
For the ones who are still interested, there are several web sites to visit with links to others, e.g.:

The ISCS - International Sand Collectors Society.
www.sandcollectors.org

Another one:
www.sandcollector.com to which you can add your name, when you are a sand collector.

Or:
james38.multimania.com/sandcollection.shtm

and last but not least the very varied and colourful site of my friend Loes Modderman, in which, beside microscopic art images you can admire many images of sand grains:
www.ScienceArt.nl
 

Most sand collectors like to trade samples, meet each other and talk about the curious things they discover.
They call sand collectors "arenophiles" or "psammofiles", awful!
With the help of more experienced persons we gradually learn more.
Some collectors are very busy in making pictures or slides of the sand grains or other funny things in their samples.
The nice part of it, is that you can combine the picture with the sand sample or show the image in your web site to enjoy or help others.

Anyway, you will surely have come to the conclusion that this is an endless hobby, as endless as there will always be sand on our planet, due to the circular course of "sand turning into stone and stone into sand".

Let us hope we never lose our capability to be astonished by nature's inventions.

I wish you many pleasant hours with your microscope!

With many thanks to Loes and Jos who added the images of some of my samples.

Comments on the article to the author, Carla Lagendijk are welcomed. Or e-mail Loes Modderman with any queries on the images.

Image credits and acknowledgements. The page background is courtesy of Wim van Egmond. The title background is derived from an image by the author, Carla Lagendijk. Thanks also to Loes Modderman for taking the sand photos and for additional help.