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Jade is a cultural term referring to two distinct mineral species: nephrite and jadeite. Both are characterized by their exceptional toughness, which is a result of their interlocking fibrous or granular crystal structures. While they can appear similar, they differ significantly in chemical composition, crystal structure, and geological origin. Nephrite is a member of the amphibole group, specifically a variety of tremolite-actinolite. Jadeite is a member of the pyroxene group. Both minerals exhibit a wide range of colors, from white to various shades of green, yellow, brown, black, and lavender.
How to Identify
- Color
- Nephrite: Typically creamy white, various shades of green (spinach green, dark green), grey, brown, black. Jadeite: Wider range of colors including white, apple green, emerald green, lavender, blue, pink, yellow, orange, brown, black. Imperial jadeite is a vibrant, translucent emerald green.
- Luster
- Vitreous to greasy, sometimes waxy.
- Texture
- Typically fine-grained, compact, and dense. Can appear smooth or slightly granular.
- Crystal Form
- Nephrite: Cryptocrystalline, interlocking fibrous aggregates (felted texture). Jadeite: Cryptocrystalline, interlocking granular aggregates.
- Cleavage
- Nephrite: Perfect prismatic cleavage (two directions at 56° and 124°), but rarely observed due to fibrous nature. Jadeite: Perfect prismatic cleavage (two directions at 87° and 93°), also rarely observed in massive forms.
- Geological Environment
- Nephrite: Serpentinized ultramafic rocks, contact metamorphic zones, often associated with tremolite-actinolite schists. Jadeite: High-pressure, low-temperature metamorphic rocks (blueschist facies), typically in serpentinite-rich environments within subduction zones.
Key Facts
- Hardness: Nephrite: 6-6.5 (Mohs). Jadeite: 6.5-7 (Mohs).
- Specific Gravity: Nephrite: 2.90-3.03. Jadeite: 3.30-3.38.
- Crystal System: Nephrite: Monoclinic. Jadeite: Monoclinic.
- Color: Nephrite: White, cream, various greens, grey, brown, black. Jadeite: White, apple green, emerald green, lavender, blue, pink, yellow, orange, brown, black.
- Luster: Vitreous to greasy, waxy.
- Transparency: Opaque to translucent, rarely semi-transparent.
- Fracture: Splintery (nephrite), granular to splintery (jadeite).
- Cleavage: Nephrite: Perfect prismatic (two directions at 56° and 124°), but rarely observed due to fibrous nature. Jadeite: Perfect prismatic (two directions at 87° and 93°), also rarely observed in massive forms.
- Composition: Nephrite: Calcium magnesium iron silicate hydroxide. Jadeite: Sodium aluminum silicate.
Quick Check
- Color: Wide range, commonly green, white, black, lavender, yellow, brown.
- Luster: Vitreous to greasy, sometimes waxy.
- Streak: White.
Physical Characteristics
- Crystal Habit: Nephrite: Dense, compact, interlocking fibrous aggregates (felted texture). Jadeite: Dense, compact, interlocking granular aggregates.
- Cleavage Type: Nephrite: Perfect prismatic, but typically not visible in massive forms. Jadeite: Perfect prismatic, typically not visible in massive forms.
- Fracture Type: Nephrite: Splintery. Jadeite: Granular to splintery.
- Tenacity: Extremely tough (due to interlocking crystal structure), making it resistant to breaking and chipping.
- Luster Type: Vitreous to greasy, sometimes waxy.
Formation
Jade forms under specific metamorphic conditions. Nephrite, a calcium magnesium iron silicate, forms in serpentinized ultramafic rocks (e.g., peridotite, dunite) or in calcium-rich metamorphic rocks (e.g., tremolite-actinolite schists) through metasomatism. Jadeite, a sodium aluminum silicate, forms under high-pressure, low-temperature metamorphic conditions characteristic of subduction zones, typically in blueschist facies rocks, often associated with serpentinite.
Usage
Historically and currently, jade is highly prized for carving and jewelry due to its exceptional toughness. It has been used for tools, weapons, ceremonial objects, and decorative items across various cultures, particularly in Mesoamerica, China, and New Zealand. Both nephrite and jadeite are used, with jadeite generally being more valuable due to its rarity and often more vibrant colors.
Age Distribution
Varies widely depending on the geological setting of metamorphism, ranging from Precambrian to Cenozoic.
Where to Find
Myanmar (Burma)
Primary source of high-quality jadeite, particularly the imperial green variety, found in alluvial deposits and in situ within serpentinite bodies in the Kachin State.
China (Xinjiang, Liaoning)
Historically significant source of nephrite, particularly from the Kunlun Mountains (Hotan/Khotan jade) and Liaoning province. Also some jadeite occurrences.
New Zealand (South Island)
Major source of nephrite, known as 'Pounamu' by the Māori people, found in metamorphic rocks and as river boulders.
Russia (Sayan Mountains)
Significant deposits of nephrite, often with attractive green and black varieties.
Canada (British Columbia)
Large deposits of nephrite, often found in massive boulders in alpine regions.
Guatemala
Historical source of jadeite for Mesoamerican cultures, rediscovered in the Motagua Valley, with a range of colors including lavender and blue.
United States (California, Wyoming, Alaska)
Nephrite deposits are found in various locations, notably in California (e.g., Big Sur) and Wyoming. Jadeite occurrences are rare but known in California.
Finding Tips
Look for specific geological environments
For nephrite, search in areas with serpentinized ultramafic rocks or tremolite-actinolite schists. For jadeite, focus on blueschist facies metamorphic terrains, often associated with serpentinite in ancient or active subduction zones.
Check for toughness and density
Jade is exceptionally tough and dense. A piece of jade will feel heavier than expected for its size and will be very difficult to scratch or break. A 'clink' test (gently tapping two pieces together) can produce a distinctive, resonant sound for genuine jade.
Observe luster and texture
Genuine jade typically has a vitreous to greasy luster when polished, and a smooth, often waxy feel. The texture is cryptocrystalline, meaning individual crystals are not visible to the naked eye.
Perform a scratch test (with caution)
While not definitive, jade (both nephrite and jadeite) is harder than steel (Mohs 6-7). A steel knife should not scratch it. However, this test can damage the specimen and should be used with care on a less visible area.
Consider specific gravity
Jadeite (3.30-3.38) is denser than nephrite (2.90-3.03). This can be a useful differentiating factor for experienced collectors using hydrostatic weighing.
Similar Rocks
Serpentine
Mg3Si2O5(OH)4
Also known as: Bowenite, Antigorite, Chrysotile
Prehnite
Ca2Al2Si3O10(OH)2
Also known as: Grape Jade
Grossular Garnet
Ca3Al2(SiO4)3
Also known as: Hydrogrossular, Transvaal Jade
Vesuvianite
Ca19(Al,Mg)13(B,Al,Fe)5(SiO4)10(Si2O7)4(OH,F,O)10
Also known as: Idocrase, California Jade
Chalcedony
SiO2
Also known as: Chrysoprase
Scientific Classification
- Mineral Class
- Silicate
- Group
- Nephrite: Amphibole Group (Tremolite-Actinolite Series). Jadeite: Pyroxene Group.
- Crystal System
- Monoclinic (for both nephrite and jadeite).
- Chemical Formula
- Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2. Jadeite: NaAlSi2O6.
- Composition
- Nephrite: Calcium magnesium iron silicate hydroxide. Jadeite: Sodium aluminum silicate.
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