Jade (Nephrite or Jadeite)

Hardness: Nephrite (6-6.5), Jadeite (6.5-7); Color: Typically green (various shades from pale to dark, sometimes with white, brown, or black inclusions), but can also be white, pink, lavender, red, yellow, orange. The beads in the image range from light to medium green. Luster: Vitreous to greasy; Crystal Structure: Monoclinic; Cleavage: Good in two directions (nephrite is fibrous, jadeite prismatic); Specific Gravity: Nephrite (2.95-3.1), Jadeite (3.25-3.43)

Jade forms under conditions of high pressure and relatively low temperature. Nephrite is a metamorphic rock formed from the alteration of ultramafic rocks (like serpentine) or dolomitic limestones, often found in subduction zones. Jadeite is formed in high-pressure, low-temperature metamorphic environments typically found in subduction zone mélanges. The geological age varies depending on the specific deposit, often associated with Mesozoic or Cenozoic tectonic events.

Predominantly used for ornamental purposes, including carvings, jewelry (beads, pendants, rings), and sculptures. It has been highly valued in many cultures, particularly in East Asia, for its beauty and symbolic meaning. Due to its toughness, it was historically used for tools and weapons.

There are two distinct minerals commonly referred to as 'jade': Nephrite and Jadeite. While they look similar and are both extremely tough, they have different chemical compositions and crystal structures. Jadeite is generally rarer and considered more valuable, especially Imperial Jade (a vibrant emerald green jadeite). Nephrite is composed of interlocking fibrous crystals, making it exceptionally tough, while Jadeite has a granular structure. Ancient civilizations in China and Mesoamerica highly revered jade, often associating it with immortality and royalty.

Field identification can be challenging. Key indicators include its characteristic toughness (difficult to scratch or break), waxy or greasy luster when polished, and often translucent to opaque appearance in various shades of green. It's often found in metamorphic belts, particularly alongside serpentine or in river gravels where it has been eroded from its source rock. Common locations include Myanmar (Burma) for fine jadeite, and China, Russia, Canada, the US, and New Zealand for nephrite. To distinguish between nephrite and jadeite in the field without advanced testing, one might look for the specific density (jadeite is denser) or examine the texture (nephrite often appears more fibrous). For collectors, identifying quality involves examining color consistency, translucency, and the absence of significant flaws or inclusions.