This unusual quartz sand from Florida has a unique property - when you walk on it it squeaks loudly. The cause is the non abraded highly fresh surfaces rubbing together as opposed to normal beach sand which is highly frosted.

In this set, I take a closer look at this sand with three different types of illumination: Backlit, Side light, and Dark field. Lets go over briefly what the difference is and when its used.

1. Backlit. This is the normal under the stage lighting you use with most microscopes. A bright collimated beam of light gets concentrated by a second condenser lens and appears as a sharply illuminated point on the subject from behind. Thus the field is bright and is used only subjects that are highly transparent.

2. Side Light. When we turn off the under stage illumination and use a bright fiber optic beam shooting it from the side across the specimen. This is similar to the view the eye would see under strong lighting.

3. Dark Field. Here, a special dark field stop was made and placed inside the condenser lens. This effectively backlights the subject but with a dark field behind so the subject appears to light up by diffraction effects. Think of it like shining a flashlight from all sides up at an angle while against a dark background.

Click all images for the full size 1290 x 960 image!

60x Backlit.

60x Side Light.

60x Dark Field. This seems to be the best for illumination on the clear grains. They look like boulders - But are tiny sand grains!

150x with the Dark field mask in. Note the faces have crystalline details.

600x view of one of the grains surface. Sub crystal forms cover the top, and the back lit quality of the dark field makes the grains almost look metallic in nature.