Iridescence: All Colors, All the Time Quiz

Answer: microscopic structure

Most colors perceived by the human eye are due to pigment molecules, which give off color by absorbing some light and reflecting the rest. Iridescence is sometimes called 'structural color' because the object's structure gives off its colors. There are many different ways an object can show iridescence, such as diffraction, double refraction, or light waves interfering with each other.

Answer: oil

Though generally indicative of pollution, thin films of oil or gasoline on water can nonetheless create a beautiful rainbow effect. Similar to soap bubbles, a thin film of oil creates thin-film interference, and is caused by the reflection and refraction of light through the layers of water, oil, and air. Light waves passing through the oil interfere with one another, causing a rainbow sheen of varying colors.

Answer: nacre

Also known as mother-of-pearl, nacre is a compound created by many molluscs as an inner layer of their shells. Coats of nacre can accumulate to create a pearl. Nacre is composed of numerous tiny platelets of calcium carbonate, each about the thickness of a wave of visible light, and is very strong.

The platelets cause constructive and destructive interference to light, resulting in iridescence.

Answer: compact disc

A CD is made with polycarbonate plastic, coated with a thin, reflective layer of aluminum. Tiny pits, only nanometers deep, are embedded in the plastic, and a laser moving across the pits changes in intensity, causing data to be read. Like many other objects, the thin layers of patterned grooves and reflective surface cause light to refract through the CD, giving it an iridescent shine under regular light.

Answer: False

The peafowls endemic to Asia are noted for their iridescent feathers. While the males (peacocks) are particularly famous for their extravagant feathers, the females (peahens) do have iridescent feathers around their head and neck regions. Peafowl have very loud calls, and tend to forage on the ground, though they have no difficulty flying. Asian peafowl come in two species, green and blue (or Indian); the latter is the national bird of India.

Answer: ammolite

Ammolite is a gemstone primarily made of the fossil shells of ammonites. Like many shellfish, ammonites contained nacre, and as a result, ammolite is iridescent. Ammolite was officially declared a gemstone in 1981, and is one of the few gemstones derived from living organisms. Most of the world's ammolite comes from the Rocky Mountains of North America.

Answer: oxidation

Like most elemental metals, bismuth is a dull grey color in its native state. Unlike most metals, bismuth can be 'grown' in a stairstep structure with an iridescent color. This color comes from a thin patina of bismuth oxide that reflects light and causes its beautiful coloring. Differences in the thickness of the oxide cause it to take on many colors.

Answer: Yes

Iridescence is not something typically associated with meat, but it does happen. When meat is cut, the fibers in the meat can become grooved in shape. Much like other iridescent materials, these grooves diffract light, causing the iridescent sheen. Such meat is not tainted or dangerous in any way and is just as safe to eat as non-iridescent meat.

Answer: opal

Opal is a type of silica, the same material that makes up quartz, sand, and glass. Precious opal is created when silica spheres are tightly packed together. If the spheres are packed tightly enough, light will diffract through it, giving off a rainbow sheen. Nearly all of the world's opal comes from Australia, and the vast majority of that comes from the state of South Australia.

Answer: counterfeiting

Though its color does change when viewed from different angles, the blue morpho butterfly appears blue from most angles. Its iridescence is caused by the prism-like shape of the scales on its wings. The microscopic patterns of the blue morpho's scales are being studied to create security measures to help deter counterfeiting, such as that of money.

The patterns are so fine that they would be nearly impossible to replicate.