Sand can look beautiful under the microscope. Of course there are many different types of sand and I studied various types with the microscope. When someone I know goes on a distant vacation, I usually ask to bring back some sand. The colours of sand grains indicate which minerals they contain. Red sand grains, for example, derive their color from the presence of iron-containing minerals. The purer the sand, the whiter. White sand consists largely of quartz (silicon dioxide, SiO2) and the less contaminants it contains, the whiter it will be. The mineral olivine is a silicate containing magnesium and iron, (Mg, Fe) 2SiO4, and its presence causes a green color in sand grains. On islands with a volcanic past you can find black sand on the beach and this sand consists largely of basalt, which was formed by the rapid solidification of lava.

Here are some photos of sand from Australia.

Red sand from the Outback in Australia fotographed in darkfield illumination. Objective: Olympus 10/0.25 (37 mm).

Red sand from Australia photographed in darkfield illumination with a Leitz dry darkfield condensor. Direct projection with Olympus objective 10/0.25 (37 mm).

Red sand from the Outback in Australia. Plan 4/0.10.

Also from Australia: sand as white as sugar and of a high purity. This sand consists almost entirely of quartz. Photographed with incident light. Objective: Leitz 4/0.12.

Sand from the English coast.

Sand from a beach at South Coast of England fotographed in brightfield illumination. Objective: Carl Zeiss 3.2/0.07.

Sand from Surinam.

Sand from 'Berg en Dal', Suriname. Fotographed with a combination of brightfield illumination and incident light. Objective: Carl Zeiss Neofluar 6.3/0.20

I brought this sand from a beach in Funchal. The sand has a volcanic origin and the beaches there are black.

Black sand from a beach in Funchal photographed with incident light from one side. Direct projection with a no-name plan 4/0.10 objective.

The same sand as in the previous photo, this time photographed with a combination of incident light (from one side) and darkfield with a dry Leitz darkfield condenser. Direct projection with a generic plan 4/0.10 objective.

Sand from different locations in the Netherlands.

Sand from the Kennemerduinen, location ‘t Wed. Fotographed with a combination of brightfield illumination and incident light. Objective: Leitz 4/0.12.

Sand from location ‘Vossenberg’, Meijel (Limburg). Fotographed with incident light. Objective: Leitz 4/0.12.

Sand from a beach at Texel, location 'Mok'. Fotographed with darkfield illumination. Objective: Carl Zeiss Neofluar 6.3/0.20.

Sand from a beach at IJmuiden photographed in brightfield (left, Carl Zeiss 3.2/0.07) and darkfield (right, Zeiss Neofluar 10/0.30).

Sand from a construction site at a road fotographed with incident light. Objective: Carl Zeiss Neofluar 6.3/0.20.

Sand from Kijkduin fotographed with a combination of darkfield illumination and incident light. Objective: Carl Zeiss Neofluar 6.3/0.20.

This construction sand was lying behind my house and I was surprised by the diversity of colors the sandgrains had. Photographed in darkfield illumination with Olympus 4/0.10. Camera: Nikon 1 J1.

The same construction sand as in the previous photo, also in dark field illumination, but now photographed with Zeiss-Winkel 2.5/0.06. Camera: Olympus PEN E-PL1.

Once again the construction sand, again photographed in darkfield but now with Carl Zeiss 3.2/0.07 by means of direct projection. The image of the objective was projected onto the sensor of a Canon 600D without the intervention of an eyepiece or projective.

Before I put sand under the microscope, I wash it with tap water. I add some water to the sand in a jar and then shake it. I let the sand grains settle for a while and then pour off the water. I do this a few times until the water remains clear. Plant remains and other contamination usually float to the top and are removed in this way. I suck up some of the washed sand with a pipette and put this on a slide. Because the sand is suspended in water, the sand grains become more transparent.

For sand photography I use objectives 2.5x - 10x, depending on the grain size and the effect I want to achieve. I usually use normal achromats and some of them are fully corrected, i.e. they can be used for photography with or without an eyepiece. Some examples of fully corrected objectives are Zeiss-Winkel 2.5/0.06, Carl Zeiss 3.2/0.07 and Olympus 4/0.10 (37 mm parfocal length). I usually use these objectives with an Olympus P10x eyepiece that then serves as a projection eyepiece. Some post-focusing is always necessary. I also photograph sand with the objectives mentioned by means of direct projection: the image of the objective is projected onto the camera sensor without the intervention of an eyepiece or projective. This is not possible with every microscope because with some microscopes, disturbing reflections can occur due to the lack of optics in the photo tube. For direct projection I use, for example, a black Leitz microscope, the Laborlux II, with which this works fine.

When I photograph sand in brightfield illumination, I usually do not use a condenser. I then use a Noviplast LED lamp on batteries as a light source. This gives a diffuse light that illuminates the entire aperture of the objective. I place the lamp on the condenser holder and this is set as high as possible. For darkfield lighting I use a darkfield condenser or just a black circle that I place on the LED lamp.

Illumination of sand with a Noviplast LED lamp. Left: LED lamp placed on condenser holder. Left: slide with sand in water.

Street sand photographed with brightfield illumination (left) and darkfield illumination (right). Both illumination techniques show different details. The colours and the 'glassy' character of the sand grains are particularly visible in darkfield. Objective: Carl Zeiss 3.2/0.07.

I experimented a bit with different illumination techniques. I noticed that some combinations of different illumination techniques can give interesting results. The colors in sand grains, for example, become more visible with darkfield illumination or with incident light at an angle. For incident light, I usually use a Jansjö LED lamp (IKEA) where I apply a diffuser or a piece of paper to get a more diffused light. This reduces disturbing light reflections.

The effect of different lighting techniques becomes clear in the following images. Here I illuminated the sand in different ways and I also tested combinations of different illumination techniques. I also looked at the effect of the color temperature of the light source. The Jansjö LED lamp normally gives a yellowish light that can be corrected with a blue filter to create white light. However, with a higher color temperature, the sand grains appeared to have less pronounced colors.

Sand from the Kennemerduinen photographed with Leitz 4/0.12 and illuminated in different ways. Upper 3 images, from left to right:

1. darkfield illumination,

2. brightfield illumination

3. oblique illumination.

Lower 3 images, from left to right:

4. Jansjö with blue filter, illumination from 1 site

5. Jansjö with blue filter, illumination from 1 site combined with brightfield illumination

6. Jansjö without blue filter, illumination from 1 site combined with brightfield illumination

It is striking that transparent sand grains with the combination of bright field illumination and illumination from one side appear very dark, as if they are black (images 5 and 6). This, of course, does not correspond to reality. Actual color differences are better represented with pure incident light (illumination from 1 side), brightfield and darkfield illumination.