Salt is an essential ingredient in every kitchen. It is easy to obtain and safe to handle. Therefore, it is a great material to start for kids and young students when using microscopes to explore the world. They look different with the naked eye, and with different types of microscopes. In addition, we got to learn what the crystal looks like!
What is salt
At first glance, this is a simple question. It’s a seasoning ingredient in the kitchen that makes food salty and taste well! Structurally, salt is made from positively charged ions (sodium ions), and negatively charged ions (chloride ions) and organized into a cubic pattern.
In a broad term, salt refers to a chemical compound that contains both cations and anions such as NaCl (Na+ and Cl–), MgCl2 (Mg2+ and Cl–), etc.
What is crystal
Everything in the world is made from very tiny building blocks, called atoms. If atoms arrange in a repeating pattern, this forms a crystal. More atoms can add to this structure in the same pattern, making the crystal bigger and bigger.
Some parts of a crystal’s structure are weaker than other parts, so the weaker parts break first when a crystal is crushed.
[In this image] The atomic structure of a salt grain.
Salt is made of Na+ and Cl– ion, and these ions arrange in a cubic repetitive pattern.
How to observe salt under a microscope
The material you need
- Blank microscope slides and coverslips
- A variety of salts
- Compound microscope/ dissecting microscope/ digital microscope
Put several grains of salt on a microscope slide. If you use a compound microscope, put a coverslip on it (prevent it from scratching the objective lens).
Start with a lower magnification. Look at the shape, color, size, and texture of the salt crystals, then shift to the high power objective lens. See if you can see some details.
If you use a dissecting microscope or a digital microscope, you don’t have to put a coverslip. There is lots of space between the objective lens and your specimen.
What will you see?
I am using a digital microscope as an example. When a specimen such as salt is a light color and transparent, you could place a piece of black paper below a microscope slide. A darker background makes clear crystal stands out and easy to observe its details.
[In this image] Objects in the white background are easy to spot their color, but transparent objects in the darker background are easy to see their outline and structure.
Morton table salt
[In this image] Morton salt under a digital microscope with a low magnification.
[In this image] Morton salt under a digital microscope with high magnification. You can appreciate their cubic shape and their size are pretty consistent.
Try to look at different types of salts, you will notice their distinct physical properties, including their geometric shape, size, and what it’s made of.
[In this image] Different salts under a digital microscope with a low magnification. You can observe their physical properties, including sizes, shapes, and colors.
Different types of salt
I have 3 different types of salt in my kitchen, so let’s talk about their difference.
Morton table salt
Morton table salt is the most common type of kitchen salt. It is all-purpose salt and uniformly shaped crystals. These uniformly shaped crystals come from their production process – dissolving salts, boiling the saltwater, refined it to a certain size.
Himalayan pink salt
Himalayan pink salt is harvested from salt beds formed more than 250 million years ago in the Himalayan mountain. The rich pink color comes from the 84 natural minerals embedded in the rock salt. Its overall sodium content is lower when compared to table salt or sea salt.
[In this image] Himalayan pink salt under a digital microscope with a low magnification. Here are a few grains of Himalayan pink salt. Their color ranges from white to pink.
[In this image] Himalayan pink salt under a digital microscope with high magnification. It really looks like a rock, which also reflects its origins from a salt mine.
The black lava salt is an Icelandic geothermal flaky sea salt blended with activated charcoal. The activated charcoal is a natural detoxifier that has health benefits and also gives lava salt black color. They use geothermal energy from the hot geysers to make sea salt.
[In this image] Lava salt under a digital microscope with a low magnification. You can see black charcoal covering the sea salt crystals.
[In this image] Lava salt under a digital microscope with high magnification. You can see the sea salt cubic structure and black charcoal all over the surface. Black charcoal gives lava salt black color.