Calcite's Dividing Lines

Purpose of Demonstration: To demonstrate the light splitting ability of calcite and other gemstones in a daylight environment. Objects viewed through a calcite crystal will show the extreme doubling where the calcite is splitting the beam of light into two distinct beams. This demonstration can be used in conjunction with the laser demonstration of the other page.

Equipment Required: An optical quality calcite crystal and a straight line printed on a piece of paper.

Suggested Grade Level: Middle School and up to gemological teaching level.

Degree of Difficulty: Easy.

Cautions: None

Here's how it works: Simply place the calcite over printed words, or in the case of the straight line you will see the divided lines running as a single line into the stone, then divides, then back to a single line again. Graphically demonstrated by calcite.

Here is what you should see:

The calcite is actually taking the line you see and splitting the image into two lines. This is a property that makes calcite very important to gemologists for making the calcite dichroscope. This is an instrument that uses the above property of calcite to allow the gemologists to see different colors being transmitted by a gemtone that our eyes could not otherwise see. The dichroscope looks like this:

It has two pieces of calcite inside that split the light up coming through a gemstone, just like it does in the calcite above. This lets the gemologist see the different colors that the gemstone is producing.

Here is a picture of what it looks like to look through a calcite dichroscope at a gemstone called andalusite. This stone looks brownish red in real life, but when we look at it through the dichroscope, we can see that the gemstone is actually producing colorless of white.... and brown red color. This helps us to identify this stone as an andalusite.

Just another of the wonderful ways that nature gives us to study who gemstones create such beautiful colors.

The image below was taken through a large piece of optical quality calcite and donated to us by the Amazing Gem and Mineral Museum for study. This gives you an amazing view of what calcite can do with light.

To learn more, Visit the Amazing Gem and Mineral Museum to see this and other calcite specimens.

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