Nephrite Jade
Actinolite-Tremolite Series var. Nephrite · Semi-Precious Gemstone / Ornamental Stone
Crystal System
Monoclinic; typically occurs in massive, microcrystalline (cryptocrystalline) aggregate forms with an interlocking fibrous 'felted' structure.
Mineral Group
Silicates; Inosilicate class (Amphibole group)
Chemical Formula
Ca2(Mg, Fe)5Si8O22(OH)2
Formation Process
Metamorphic; specifically regional metamorphism where ultramafic rocks (like serpentinite) react with fluids or contact metamorphism between dolomite and siliceous rocks.
About This Crystal
An opaque to translucent dark green or grey-green stone with a greasy to vitreous luster. This specimen shows a rugged, somewhat dimpled texture typical of alluvial 'mutton fat' or river-worn rinds, with a waxy surface and deep mossy tones.
Physical Characteristics
Color: Dark spinach green to greyish; Streak: White; Cleavage: Formally two directions at 56 and 124 degrees, though rarely visible in massive form; Fracture: Splintery to uneven; Specific Gravity: 2.90–3.03; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.606–1.632; Birefringence: 0.023; Pleochroism: Weak; Optical phenomena: Can occasionally show chatoyancy if fibrous but usually opaque massive.
Hardness & Durability
Origin Region
British Columbia (Canada), New Zealand, China (Hotan), Russia, and Wyoming (USA); found in metamorphic environments involving serpentinite.
Hardness & Durability
Mohs hardness: 6.0–6.5; Toughness: Exceptional (highest of any natural stone due to interlocking fibrous structure); very stable and resistant to fracturing.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid harsh chemicals and ultrasonic cleaners if cracks are present. Store away from harder gems like Diamond or Sapphire which can scratch it.
Rarity & Value
Common to Uncommon; value is driven by color uniformity, translucency, and lack of black inclusions (chromite/magnetite). Higher grades are used for fine jewelry and carvings.
Special Characteristics
Renowned for its extreme toughness—it is more difficult to break than steel of the same thickness. It may exhibit a 'greasy' feel when polished.
Lore & History
Historically known as the 'Axe Stone' or 'Stone of the Kidneys' (Lapis Nephriticus). It has been used for millennia in China as a symbol of purity and immortality and by the Maori of New Zealand for 'Mere' clubs and 'Hei-tiki' pendants.