Pink Amethyst, Rose Quartz and Pink Quartz: Key Differences
When you get involved in the gemmology world, you learn quickly that Mother Nature does not have a neat set of rules for classifying gemstones and crystals. Arguably, mineral and gem classification is vast and complex, and depending on who you ask about the differences between these materials, you may get different answers.
Rose Quartz and Pink Quartz
Generally, rose quartz is the name reserved for pink-coloured crystalline quartz. By this definition, rose quartz and pink quartz are the same thing.
Rose quartz commonly grows in a massive crystal habit. Massive is the name given to crystal habits where it is shapeless, with no distinctive external crystal shape. This can also be described as anhedral, which means it forms with no well-formed crystal faces but instead with a mineral grain texture.
Pink quartz (also called Canga Rosa) is the name generally given to rose quartz that has a euhedral formation, meaning it forms with easily recognised crystal faces. This type of quartz is very rare and expensive. Pink quartz is sometimes also referred to as crystallised rose quartz.
Formation aside, let's now take a deeper look into what causes the colouring of these two quartz crystals:
Rose quartz
In a study from 2001 (American Mineralogist, Volume 86, pages 466–472, 2001), scientists looked at rose quartz from around the world. They found really tiny pink fibres inside the quartz. These fibres are what make the rose quartz pink.
Inside these fibres, iron and titanium interact in a particular way that changes how the stone absorbs light. This interaction is specifically strong at a specific light wavelength (500 nanometers), giving rose quartz its unique pink colour.
These fibres look a lot like another mineral called dumortierite, especially when examined with scientific tools (FTIR and Raman spectra). But they're not exactly the same. There are some differences, meaning these fibres might be related to dumortierite but aren't the same.
The study also confirmed that these pink fibres are found in rose quartz from many different parts of the world. Depending on the quartz, these fibres can be in various shades of pink, and they noticeably affect how the colour changes when viewed from different angles.
Pink quartz
The colour of pink quartz is likely due to a combination of factors involving aluminium and phosphorus replacing silicon in the quartz structure and exposure to natural gamma radiation. This gamma radiation irradiates the quartz, leading to the development of its pink colour.
This process is distinct from the colouration process in rose quartz, making pink quartz unique in its formation and appearance.
Pink Amethyst
A study was conducted on pink amethyst geodes from the El Choique Mine in Patagonia, Argentina (Mineralogical Record Vol. 51, No. 2, 2020). This article states that based on their research (using optical, spectroscopic, Raman and micro-chemical analyses), pink amethyst is neither rose quartz or pink quartz.
Both traditional amethyst (purple variety) and pink amethyst get their colours from iron. The type of iron and how it's included in the crystals differ for each.
Traditional amethyst is purple mainly because of iron impurities mixed in with the quartz. The iron and how the crystal forms play a significant role in giving amethyst its purple colour.
Pink amethyst's colour comes from iron too, but in a specific way. Two key things are happening:
Some iron makes the amethyst a light purple.
Other iron inclusions, mainly hematite, add a red tint to it.
So, while both types of amethyst have iron in them, the way the iron is present in the crystal structure is different. In pink amethyst, this mix of light purple and red iron creates its unique pink colour.
In Summary
All three of these have variances in how they get their colour and how they are formed. Giving them different names can provide clarity on the type of material you're working with or looking to purchase.
Further Reading and studies referenced in this article:
Fibrous nanoinclusions in massive rose quartz: The origin of rose coloration - American Mineralogist, Volume 86, pages 466–472, 2001
Pink Amethyst From the El Choique Mine, Patagonia, Argentina - Mineralogical Record Vol. 51, No. 2, 2020
