Microscopy of sand

Sand can look beautiful under the microscope. Of course there are many different types of sand and so far I have only studied a few 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. I have only just started doing microphotography of sand and some images are shown in this article.

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

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

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

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

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.

Technique

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. I always suspend the sand grains in a drop of water, which makes them more transparent.