Dioptase is a stunning emerald-green copper cyclosilicate mineral with the chemical formula CuSiO3·H2O. It forms beautiful, vibrant green crystals that are often transparent to translucent and exhibit a vitreous to adamantine lustre. Dioptase crystallizes in the trigonal system and is known for its well-formed, prismatic crystals. Large crystals are rare, clusters of small crystals are more commonly found. Dioptase is also known to be pyroelectric meaning that it can become electrically polarised and generate a temporary voltage. Tourmaline also has this property - pyroelectric crystals often attract dust as a result.
Dioptase is typically found in the oxidation zones of copper deposits. Major deposits have been discovered in various parts of the world, including Kazakhstan, Namibia, the Democratic Republic of Congo, and the United States (Arizona and California).
History and Cultural References
Dioptase was categorised first by JC De Lamétherie in 1793 as a ‘primitive version of emerald’. Russian mineralogists mistook it for emerald due to its intense green colour. Whilst photographing pieces for this blog I found an emerald hiding in the dioptase department, it was only on closer inspection that the imposter revealed itself!
It also went by the names of achrite, emeraudine, copper emerald or kirghisite. Three main things enabled mineralogists to differentiate dioptase - its lower hardness, its higher specific gravity and the fact that its green colour was due to copper. It was only them that it was recognised as a new mineral.
The name "dioptase" is derived from the Greek words "dia," meaning "through," and "optos," meaning "visible," referring to the mineral's transparency.
Due to the intensity of its colour, dioptase was also used as a pigment in painting. The use of dioptase as a green pigment can be traced back to Neolithic times, including the famous group of ceramic figures of ‘Ain Ghazal dating from the 9th century BC, in today’s Jordan. Three of these thirty-two ritual statues, half-size human figures modelled in white plaster, had their eyes formed with a cowrie shell, a bitumen pupil, highlighted with a vivid green dioptase pigment.
Despite its beauty, dioptase has never been widely used in ancient jewellery, likely due to its relative rarity and lower hardness. Being 5 on the Mohs scale of hardness means that dioptase is softer than quartz and will not be durable enough for use in jewellery. You might just be able to mount it in a brooch or pendant that has occasional use by a careful owner.
I have seen a very small number of faceted dioptase crystals but they are very rare and I am still searching for a good one for my gem collection. Dioptase is also brittle (like emeralds) so extra care is needed.
Dioptase vs. Diopside: Understanding the Differences
Sometimes these two distinct crystals are confused, most likely because of the similar names and because dioptase is green and diopside is often green, although diopside comes in other colours as well (black, brown, yellow and blue). You can see from the table below that they have similar properties, the easiest way to tell them apart is by colour, dioptase is definitely a rich emerald green, diopside is much more of a limey grass green. You are also very unlikely to see dioptase in jewellery, diopside is used in jewellery and is sometimes referred to as Russian diopside or chrome diopside.
| Dioptase | Diopside | Emerald |
Chemical Composition | CuSiO3·H2O | CaMgSi2O6 | (Be3Al2(SiO3)6) |
Colour | Vivid emerald green | Typically green, but can also be black, brown, yellow, or blue. | Green |
Mohs Hardness | 5 | 5.5 to 6.5 | 7.5-8 |
Transparency | Transparent to translucent | Usually transparent to translucent | Transparent to translucent |
Occurrence | Found in the oxidation zones of copper deposits | Found in metamorphic and igneous rocks | Hydrothermal veins in granitic rocks |
Locality | Kazakhstan, Namibia, DRC, USA | Siberia, Pakistan | Columbia, Brazil, China, worldwide |
Colouration | Green colour from copper | Green colour from chromium | Green colour from chromium and/or vanadium |
Metaphysical Properties of Dioptase
Dioptase is believed to be a powerful stone for emotional healing and release. It is said to help clear past traumas and emotional blockages, promoting forgiveness and compassion. It is thought to encourage a heart-centered approach to life, fostering love and emotional balance.
This mineral is associated with spiritual growth and insight, aiding in the development of a deeper understanding of oneself and the universe. It is often used in meditation to enhance spiritual awareness and connect with higher consciousness.
Dioptase is reputed to stimulate creativity and assist in the manifestation of one's goals and desires. It is believed to help users visualize their dreams and take the necessary steps to achieve them. In the realm of physical healing, dioptase is thought to support the body's detoxification processes and enhance the immune system. It is also considered beneficial for the heart and circulatory system, though these claims are based on belief rather than scientific evidence.
Conclusion
Dioptase, with its vivid emerald-green colour and striking crystal formations, is a gem that captivates both the eye and the soul. Discovered in the late 18th century and often mistaken for emerald, dioptase has carved out its niche in the world of minerals and gemstones. Though relatively soft for extensive jewellery use, its beauty makes it a prized piece for collectors and occasional wear.
In the metaphysical realm, dioptase is celebrated for its emotional healing properties, spiritual growth facilitation, and creative inspiration. Whether you are drawn to its physical beauty or its purported energetic qualities, dioptase is a gem that offers a rich tapestry of benefits for collectors and enthusiasts alike.
Check out our dioptase crystals for sale in the Geminlogical shop.
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