What is Jadeite?
Jadeite is a pyroxene mineral with the chemical formula NaAlSi2O6. It has a single axis. Depending on the composition, it has a Mohs hardness of 6.5 to 7.0. The mineral has a specific gravity of about 3.4.
The name jadeite is derived from the Spanish phrase "piedra de ijada," which means "stone of the side". The term nephrite is derived from the Latin version of the name, lapis nephriticus, which is a different mineral from the common name jade.
Jadeite Stone Chemistry
Other pyroxene end members that form solid solutions with jadeite include augite and diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr endmember). Omphacite is a type of pyroxene that contains both the jadeite and augite endmembers. Jadeite forms in metamorphic rocks under high pressure and relatively low temperature. Albite (NaAlSi3O8) is a common mineral in the Earth's crust with a specific gravity of about 2.6, which is significantly lower than that of jadeite. Albite degrades under increasing pressure to form the high-pressure assemblage of jadeite and quartz.
Jadeitite refers to rocks that are almost entirely composed of jadeite. Jadeitite appears to have formed from subduction zone fluids in association with serpentinite in all well-documented occurrences. Jadeitite is resistant to weathering, and boulders of jadeitite formed in serpentine-rich environments can be found in a variety of environments.
Jadeite Stone Colour
The colour of jadeite typically ranges from white to pale apple green to deep jade green, but it can also be blue-green (as in the recently rediscovered "Olmec Blue" jade), pink, lavender, and a variety of other rare colours. Chloromelanite is a dark green to black mineral. The presence of trace elements such as chromium and iron has a large impact on colour. Its transparency ranges from opaque to nearly clear. Colour and translucency variations are common even within a single specimen.
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Where is Jadeite Found?
Jadeite has been found in California, the United States, Myanmar, New Zealand, Guatemala, and Itoigawa, Japan; other jadeite locations include Kazakhstan, Russia, British Columbia, Canada, Italy, and Turkestan.
What is Imperial Jade?
Originally, it was assumed that all jade objects were made of the same material. However, in 1863, a Frenchman named Alexis Damour discovered that "jade" could be separated into two minerals: jadeite(imperial Jade) and nephrite.
The mineral compositions of jadeite and nephrite are markedly different. Nephrite is a magnesium-rich amphibole, whereas jadeite is aluminium-rich pyroxene. However, in the eyes of the average person, the two minerals have very similar physical properties.
Physical Properties of Jadeite and Nephrite
What is Jadeite Used for?
Over 180 axe heads made from jadeitite quarried in northern Italy during the Neolithic era have been discovered across the British Isles. Due to the difficulty of working this material, all of the axe heads found are thought to be non-utilitarian and to have represented some form of currency or be the products of gift exchange.
Many jadeite beads and axe heads, as well as the remains of Neolithic jadeite workshops, have been discovered in Itoigawa, Japan. These beads and axes were traded throughout Japan and the Korean Peninsula and were made by the Itoigawa region's oldest known jadeite-using culture.
FAQs on Jadeite
1. What is Jadeite and how is it defined geologically?
Jadeite is a hard, dense, and rare pyroxene mineral with the chemical formula NaAlSi₂O₆. Geologically, it is classified as a silicate and is one of the two distinct minerals that are commonly referred to as jade, the other being nephrite. Jadeite is formed under high-pressure, low-temperature conditions typically found in metamorphic rocks associated with subduction zones.
2. What is the main difference between Jadeite and Nephrite?
While both are called 'jade', Jadeite and Nephrite are different minerals. The key differences are:
- Composition: Jadeite is a sodium aluminium silicate (a pyroxene), while Nephrite is a calcium magnesium-iron silicate (an amphibole).
- Hardness: Jadeite is harder, ranking 6.5 to 7 on the Mohs scale, whereas Nephrite is slightly softer at 6 to 6.5.
- Colours: Jadeite comes in a wider range of colours, including vibrant greens, lavender, red, and black. Nephrite is typically found in shades of green, white, and grey.
- Rarity and Value: High-quality Jadeite, especially the translucent emerald-green variety known as 'Imperial Jade', is much rarer and more valuable than Nephrite.
3. What are the key physical properties of Jadeite for identification?
To identify Jadeite, geologists and gemologists look for a combination of its key physical properties:
- Hardness: 6.5 to 7 on the Mohs scale, meaning it can scratch glass.
- Lustre: It has a vitreous (glassy) to greasy lustre when polished.
- Toughness: Its interlocking crystalline structure makes it exceptionally tough and resistant to breaking.
- Specific Gravity: It has a high specific gravity, typically around 3.34, making it feel heavy for its size.
- Colour: While it can be found in many colours, its most prized shade is an intense, translucent green.
4. Where is Jadeite found, with special reference to India?
The most significant source of gem-quality Jadeite is Myanmar (Burma). Other notable deposits are found in Guatemala, Japan, Russia, and the USA. In the context of the Indian subcontinent, Jadeite is not mined commercially. However, it holds historical importance. As per archaeological findings relevant to the NCERT syllabus, Jadeite tools have been discovered at the Neolithic site of Daojali Hading in the Brahmaputra Valley, suggesting ancient trade routes with regions like China or Myanmar.
5. What makes some Jadeite, like 'Imperial Jade', so exceptionally valuable?
The high value of 'Imperial Jade' is not just due to its beauty but is a combination of three key factors. First is its extreme rarity; gem-quality, translucent Jadeite is found in very few locations. Second is its unique colour and translucence, an intense, vivid emerald-green caused by chromium impurities. Third is its immense cultural significance, especially in China, where it is considered the 'Stone of Heaven' and symbolises status, prosperity, and spiritual protection.
6. Why is Jadeite considered so tough and durable for carving?
Jadeite's exceptional toughness comes from its internal microstructure. It is composed of a dense, felted mass of tiny, interlocking granular crystals. This structure effectively absorbs and distributes energy from an impact, preventing the stone from fracturing easily. While other minerals might be harder (more resistant to scratching), Jadeite's high toughness makes it incredibly durable and ideal for intricate carvings that can withstand wear and tear over centuries.
7. Does the gemstone Jadeite glow under UV or black light?
Generally, the gemstone Jadeite does not exhibit strong fluorescence under UV or black light. However, there can be confusion with a vintage American glassware product also called 'Jadeite'. This opaque green glass, popular in the early 20th century, often contained uranium as a colorant and will glow brightly under a black light. It is important to distinguish this manufactured glass from the natural mineral Jadeite, which does not share this property.
8. What is the cultural and symbolic meaning of Jadeite?
Jadeite holds deep symbolic meaning, primarily in Asian cultures. In Chinese tradition, it is associated with nobility, purity, and good fortune. It is believed to possess protective qualities, warding off evil spirits and bringing health and longevity to the wearer. In ancient Mesoamerican cultures, such as the Mayans and Aztecs, jadeite was more valuable than gold and was used in ceremonial objects and burial masks, symbolising life, fertility, and power.
