What causes rainbows in crystals?

Petter Pan

2 days ago

Transcript

00:00Have you ever noticed that some crystals have rainbows inside of them?

00:03In this video, we are re-going to take a look at what causes these rainbows, and why some

00:07crystals have them, while others do UNT.

00:10Rainbows are an optical phenomenon that occurs when light is refracted and dispersed through

00:14a transparent material.

00:15When white light enters a crystal, it can be split up into its different wavelengths,

00:19which are the different colors of light.

00:20This happens because light travels at different speeds through a material depending on its

00:24wavelength.

00:25The separation of light into different wavelengths is called dispersion, and the amount of dispersion

00:29that occurs is determined by the refractive index of the material.

00:32The higher the refractive index, the more dispersion that occurs.

00:36So why do some crystals have rainbows inside of them and others don't?

00:39It all has to do with the internal structure of the crystal and how it interacts with light.

00:43In order for a rainbow to form inside of a crystal, there needs to be enough internal

00:46surfaces for the light to reflect and refract off of.

00:49If a crystal doesn't have enough internal surfaces, or if the light doesn't interact

00:53with the crystal in a particular way, then rainbows won't form.

00:56One of the most well-known crystals for having rainbows inside of them is tourmaline.

01:00Tourmaline is a very complex crystal with a large unit cell.

01:03This means that the atoms are arranged in a very specific and intricate way inside of

01:07the crystal lattice.

01:08When light enters a tourmaline crystal, it can be split up into different colors because

01:12of the difference in refractive indices.

01:13The different colors of light then reflect off of the internal surfaces of the crystal and

01:17exit as a rainbow.

01:19Tourmaline is also unique in that it exhibits a phenomenon called asterism.

01:23A crystal has multiple refractive indices, which causes it to split light up into many

01:28different colors.

01:29You can see this in a star ruby, where you can see multiple sets of rainbows inside of

01:33the crystal.

01:34This is due to the fact that ruby has two refractive indices, which causes it to split

01:38light into two different colors.

01:40Each set of rainbows represents a different orientation of the crystal lattice.

01:43So you get two sets of rainbows, one for each orientation.

01:47Another crystal that is well known for having rainbows inside of it is topaz.

01:51Topaz is a very clear and transparent crystal that can be found in many different colors.

01:55The internal structure of topaz is simpler than tourmaline, but it still has enough complexity

01:59to cause rainbows to form.

02:00When light enters a topaz crystal, it is split up into different colors due to the difference

02:05in refractive indices.

02:06The different colors of light then reflect off of the internal surfaces of the crystal and

02:10exit as a rainbow.

02:12Topaz can also exhibit asterism, like star ruby, and you can see multiple sets of rainbows inside

02:16of a crystal.

02:17This is due to the fact that topaz has two refractive indices, which causes it to split

02:21light into two different colors.

02:23Each set of rainbows represents a different orientation of the crystal lattice.

02:27So you get two sets of rainbows, one for each orientation.

02:31And another crystal that can have rainbows inside of them is spinel.

02:34Spinel is a cubic crystal system that has a simple internal structure.

02:38However, this simplicity can lead to rainbows forming inside of spinel crystals.

02:42When light enters a spinel crystal, it is split up into different colors due to the difference

02:46in refractive indices.

02:48The different colors of light then reflect off of the internal surfaces of the crystal

02:51and exit as a rainbow.

02:52Spinel can also exhibit asterism, like star ruby and topaz, and you can see multiple sets

02:57of rainbows inside of a crystal.

02:59This is due to the fact that spinel has two refractive indices, which causes it to split

03:04light into two different colors.

03:05Each set of rainbows represents a different orientation of the crystal lattice.

03:09So you get two sets of rainbows, one for each orientation.

03:12It's important to note that not all crystals will have rainbows inside of them.

03:16For example, quartz is a very common crystal that is often used in jewelry, but you never

03:20see rainbows inside of it.

03:21This is because quartz has a very simple internal structure that does not allow for rainbows to

03:26form.

03:27Another thing that can affect whether or not a rainbow is seen inside of a crystal is the

03:29size of the crystal.

03:31If a crystal is too small, then light woe and have enough time to reflect and refract

03:34off of the internal surfaces, and a rainbow woe and be seen.

03:38However, if a crystal is too big, then the rainbow can become diffused and hard to see.

03:42The ideal size for a crystal to have a visible rainbow is somewhere in the middle.

03:46The intensity of the rainbow can also be affected by the clarity of the crystal.

03:49If a crystal is very clear and transparent, then the rainbow will be very intense.

03:54However, if a crystal is cloudy or opaque, then the rainbow will be much more difficult

03:58to see.

03:59In addition to the factors mentioned above, the color of the rainbow can also be affected

04:03by the presence of impurities in the crystal.

04:05For example, if a crystal contains iron, then the rainbow may appear more red or a red.

04:09Now let's take a look at some examples of crystals with rainbows inside of them.

04:13As I mentioned before, tourmaline is a very well-known crystal for having rainbows inside

04:17of it.

04:18Tourmaline is a complex crystal with a large unit cell, and it can exhibit asterism, which

04:22is when a crystal has multiple refractive indices, which causes it to split light into

04:27many different colors.

04:28You can see this in a star ruby, where you can see multiple sets of rainbows inside of

04:32the crystal.

04:33This is due to the fact that ruby has two refractive indices, which causes it to split light into

04:37two different colors.

04:38Each set of rainbows represents a different orientation of the crystal lattice.

04:42So you get two sets of rainbows, one for each orientation.

04:46Topaz is another crystal that is well-known for having rainbows inside of it.

04:49Topaz is a very clear and transparent crystal that can be found in many different colors.

04:53The internal structure of topaz is simpler than tourmaline, but it still has enough complexity

04:57to cause rainbows to form.

04:59Spinal is a cubic crystal system that has a simple internal structure.

05:03However, this simplicity can lead to rainbows forming inside of spinel crystals.

05:08And of course, we have to mention opal, which is a mineraloid and not a true crystal.

05:12But it's still an incredible example of rainbows inside of a natural wonder.

05:16Opal's internal structure is very unique and complex, and it is this complexity that leads

05:21to the formation of rainbows inside of opal.

05:24Opal can exhibit a phenomenon called play of color, where it displays a wide range of colors

05:28due to the diffraction of light.

05:30This diffraction occurs because opal has a very specific internal structure with thin

05:34layers of silica and water.

05:35When light enters opal, it is diffracted by these layers and separated into different colors.

05:40This is what causes the beautiful play of color that opal is so well-known for.

05:44Opal can display a wide range of colors from reds and oranges to yellows and greens to blues

05:48and purples.

05:49The colors displayed by opal are some of the most beautiful and vibrant in nature, and they

05:53are sure to impress anyone who sees them.

05:55As you can see, rainbows and crystals are a truly amazing phenomenon.

05:59They are caused by the interaction of light with the internal structure of a crystal and

06:02can result in some truly beautiful and vibrant colors.

06:05Whether you are a geologist, a crystal lover, or just someone who appreciates the beauty of

06:10nature, rainbows and crystals are sure to amaze you.

06:12If you enjoyed this video, please leave us a like and a comment down below about what you

06:16would like to see next.

06:18We really appreciate your support and we're always looking for new ideas for future videos.

06:22Thanks for watching and we hope you learned something new.

What causes rainbows in crystals?

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