Turquoise is a beautiful blue-green color that has been prized for centuries. But is turquoise actually green, or is it strictly blue? The answer lies in turquoise’s unique composition and the way we perceive color.
The Composition of Turquoise
Turquoise gets its striking color from its mix of blue and green compounds. The main compound in turquoise is copper aluminium phosphate, CuAl6(PO4)4(OH)8·4H2O. This phosphate mineral contains both blue copper ions and green aluminium and phosphate ions. These ions absorb and reflect light in a way that gives turquoise its characteristic blue-green hue.
While turquoise contains both blue and green elements, the dominance of the blue copper ions makes its color lean more towards a greenish-blue rather than a true green. Looking closely at turquoise samples shows the primary blue component with just a touch of green.
Human Color Perception
When we see turquoise, our eyes and brain process its mix of blue and green wavelengths. But we don’t perceive pure spectral colors. Instead, our color vision system assigns dominant hues to the signals coming from the eye.
In the case of turquoise, the dominant wavelength is in the blue range, at around 480 nanometers. But there is also a significant contribution from green wavelengths around 500-530 nm. Our visual system takes these combined inputs and creates the perception of a bluish-green.
| Color | Wavelength range |
|---|---|
| Blue | 450-495 nm |
| Green | 495-570 nm |
This table shows the approximate wavelength ranges for pure blue and green colors. Turquoise falls right in the middle, which is why we see it as a balance of both hues.
Turquoise in Language and Culture
Most languages treat turquoise as being primarily blue rather than green. Its names in other languages usually associate it with blue or the sky:
- French: turquoise
- Italian: turchese
- Spanish: turquesa
- Russian: бирюза (biryuza)
- Persian: فيروزه (feyrûzeh)
These names all reference blue gemstones rather than green ones. Even cultures that decorated extensively with turquoise saw it as fundamentally blue in nature.
However, in English the name turquoise does end in “-quoise”, associating it with green gems. This may be why English speakers see turquoise as slightly more green-leaning than other cultures.
Turquoise Dyes and Pigments
When turquoise is used as a dye or pigment, it produces a distinctly greenish shade. The blue copper ions get diluted when combined with fabric, paints, or other media. This allows the secondary green tones to stand out more.
Turquoise dyes and pigments appear greenest when mixed with yellowish media. This pushes the color balance away from the primary blue even further. Vibrant turquoise fabrics often contain yellow components for this reason.
Conclusion
While turquoise occupies a middle ground between blue and green, its essential color is blue. Its composition, cultural associations, and technical uses all point to a blue foundation with secondary green tones. When processing turquoise through sight and language, we categorize it as a type of blue rather than true green.
The greenish tint of turquoise is caused by aluminum and phosphate ions. But the color perception starts with the dominant blue copper ions. So turquoise is best described as a blue color with a green tinge, making it one of nature’s most amazing chameleon colors.