Jadeite is a pyroxene mineral with composition Na Al Si₂ O₆. It is hard (

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...

of about 6.5 to 7.0), very tough, and dense, with a specific gravity of about 3.4. It is found in a wide range of colors, but is most often found in shades of green or white. Jadeite is formed only in subduction zones on continental margins, where rock undergoes

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...

at high pressure but relatively low temperature. Jadeite is the principal mineral making up the most valuable form of jade, a precious stone particularly prized in China. Most gem-quality jadeite jade comes from northern

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

. Jade tools and implements have been found at Stone Age sites, showing that the mineral has been prized by humans since before the beginning of written history.

Name

The name ''jadeite'' is derived (via french: jade and la, ilia) from the

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...

phrase "piedra de ijada" which means "stone of the side". The

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

version of the name, ''lapis nephriticus'', is the origin of the term

nephrite Nephrite is a variety of the calcium, magnesium, and iron-rich amphibole minerals tremolite or actinolite ( aggregates of which also make up one form of asbestos). The chemical formula for nephrite is Ca2( Mg, Fe)5 Si8 O22(O H)2. It is on ...

, which is a different mineral that also shares the common name jade.

Properties

Jadeite is a hard, extremely tough, rare mineral of the

clinopyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe I ...

family of minerals. Though highly variable in color, it is typically apple-green to emerald-green, or less commonly white or white with spots of green. Occurrences are typically granular or massive; individual crystals are very rare, occurring only as small prismatic crystals in

vugs A vug, vugh, or vugg ( ) is a small- to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity ( folding and faulting) are partially filled by quartz, c ...

in massive jadeite. Crystals are four-sided or eight-sided in cross section and show perfect cleavage on 10at angles of 87 and 93 degrees. There is also a rare parting on 00 The interlocking crystals of massive jadeite help give it its extreme toughness. Jadeite has a

of 6.5 to 7, slightly less than that of common

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

. Fracture surfaces are sugary in texture, and sparkle from the exposed perfect cleavage on 10 Jade is relatively dense, with a specific gravity of 3.3 to 3.5 in natural specimens. The specific gravity increases with the iron content, and very pure jadeite has a specific gravity of 3.25. The luster is vitreous, or pearly on exposed cleavage surfaces, and the streak is colorless. Jadeite is translucent to transparent. Jadeite is characterized by its green color and tough aggregates of compact fibrous crystals. It can be distinguished from

by its vitreous luster on polished surfaces (polished nephrite has an oily luster) and by its higher density and

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

. Serpentine also has a lower density and refractive index than jadeite. Massive jadeite also characteristically shows a more granular texture than nephrite or serpentinite. Jadeite has a fusibility of 2.5 (making it moderately easy to fuse with a propane flame) and gives a yellow flame color. Pure jadeite has the composition and has the typical clinopyroxene structure. This consists of long chains of

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

tetrahedra in which each silicon ion is surrounded by four oxygen ions, with two of the oxygen ions shared with neighboring silica tetraheda. The chains are bonded together by aluminium and sodium ions to form the full three-dimensional structure of a jadeite crystal. The aluminium joins pairs of chains (occuping the so-called M1 site) while sodium joins the paired chains to neighboring paired chains (occupying the so-called M2 site). The resulting crystal structure belongs to the monoclinic system, with

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

''C2/c''.

Chemistry and origin

Pure jadeite has the composition . There is no significant replacement of silicon by aluminium in natural jadeite, and only very limited substitution of

ferric In chemistry, iron(III) refers to the element iron in its +3 oxidation state. In ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe3+. The adjective ferric or the prefix ferri- is often used to sp ...

iron for aluminium. However,

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

substitutes for up to 20% of the sodium, balanced by substitution of

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

ferrous In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to " ferric" or iron(III), meaning iron in its +3 oxidation state, suc ...

iron for aluminium.

Omphacite Omphacite is a member of the clinopyroxene group of silicate minerals with formula: ( Ca, Na)( Mg, Fe2+, Al) Si2 O6. It is a variably deep to pale green or nearly colorless variety of clinopyroxene. It normally appears in eclogite, which is the ...

is intermediate in composition between jadeite and

diopside Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...

. However, there is not a true

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The wor ...

series, as omphacite has its own structure that is slightly different from either pure jadeite or pure diopside, so that it is separated from either end member by a

miscibility gap A miscibility gap is a region in a phase diagram for a mixture of components where the mixture exists as two or more phases – any region of composition of mixtures where the constituents are not completely miscible. The IUPAC Gold Book defines ...

. ''Chromomelanite'' is a dark green variety of jadeite in which some aluminium is replaced by iron, while ''imperial jade'', the most valuable variety of jade, is colored an intense emerald green by traces of chromium. Jadeite-stab

Jadeite occurs with

albite Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a tectosilicate ...

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, caus ...

of the low-temperature, high-pressure

blueschist facies Blueschist (), also called glaucophane schist, is a metavolcanic rock that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures (), approximately corresponding to a depth of . The blue co ...

at destructive plate margins. Although it is intermediate in silica content between

and

nepheline Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatite ...

, it is not stable under the conditions in which these two minerals are present. Formation of jadeite requires a pressure of 10 to 25 kbar and a temperature of via the reaction: Jadeite can also form at high pressure via the reaction: At still higher pressure, corresponding to the highest

, jadeite reacts with

lawsonite Lawsonite is a hydrous calcium aluminium sorosilicate mineral with formula CaAl2Si2O7(OH)2·H2O. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. Crystal twinning is common. It forms transparent to transluc ...

to form

zoisite Zoisite, first known as saualpite, after its type locality, is a calcium aluminium hydroxy sorosilicate belonging to the epidote group of minerals. Its chemical formula is Ca2 Al3( Si O4)(Si2O7)O(O H). Zoisite occurs as prismatic, orthorho ...

and

paragonite Paragonite is a mineral, related to muscovite. Its empirical formula is . A wide solvus separates muscovite from paragonite, such that there is little solid solution along the vector Na+ K+ and apparent micas of intermediate composition is most ...

: Minerals associated with jadeite include:

glaucophane Glaucophane is the name of a mineral and a mineral group belonging to the sodic amphibole supergroup of the double chain inosilicates, with the chemical formula ☐Na2(Mg3Al2)Si8O22(OH)2. Glaucophane crystallizes in the monoclinic system. Name G ...

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavag ...

aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pre ...

, serpentine and

. Rocks that consist almost entirely of jadeite are called

jadeitite Jadeitite is a metamorphic rock found in blueschist-grade metamorphic terranes. It is found in isolated metasomatically altered rock units within serpentinite associated with subduction zone environments. Jadeitite consists almost entirely of the ...

. In all well-documented occurrences, jadeitite appears to have formed from subduction zone fluids in association with

serpentinite Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''ser ...

. Jadeitite is resistant to weathering, and alluvial boulders of jadeitite released from the serpentine-rich environments in which they formed can have weights of up to tons. Raw specimens having Burmese tax stamps or polished slots for evaluating quality are prized by some collectors.

Colors

Jadeite's color commonly ranges from white through pale apple green to deep ''jade'' green but can also be blue-green (like the recently rediscovered "Olmec Blue" jade), pink, lavender and a multitude of other rare colors. ''Chloromelanite'' is a very dark green to black variety. Color is largely affected by the presence of trace elements such as chromium and iron. Its translucence varies from opaque to almost clear. Variations in color and translucence are often found even within a single specimen.

Occurrence

Significant occurrences of jadeite are isolated and rare. It is found exclusively in high-pressure, low-temperature metamorphic rock of continental margins. Here it may be found as pods or veins or as disseminated grains. Deposits are found in

, the Alps, Russia, California, Japan, and

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

. In the

Franciscan Complex The Franciscan Complex or Franciscan Assemblage is a geologic term for a late Mesozoic terrane of heterogeneous rocks found throughout the California Coast Ranges, and particularly on the San Francisco Peninsula. It was named by geologist Andrew ...

of California, jadeite is associated with glaucophane, aragonite, muscovite, lawsonite, and quartz. However, occurrences of

lapidary Lapidary (from the Latin ) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A la ...

quality are almost exclusive to

. Stream boulders of the

Uyu River The Uyu River, also pronounced Uru River (''Uyu Chaung'' in Burmese), is a river in northern Myanmar, formerly Burma. It is a major tributary of the Chindwin River, itself the largest tributary of the country's chief river, the Ayeyarwady. Its s ...

remain an important source of jadeite.

Uses

Jadeite is the dominant mineral of the most desirable variety of jade. This was prized in traditional Chinese culture, where it was worked into a great variety of beautiful ornaments and utensils. Jadeite was also used by Stone Age peoples for implements and weapons. Jade received its name, "piedra de ijada" ("stone of the side"), because it was once thought to cure kidney ailments when applied to the side of the body.

Jade

Jadeite is one of two minerals recognized as the

gemstone A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, ...

jade. The other is

. Occasionally, other minerals such as serpentine or

are sold as jade, but the difference can be determined by cleavage and hardness. Jadeite jade is the most valuable form, with the highest-quality material commanding prices well in excess of $200 per carat . Jadeite jade first came into significant use in China only towards the end of the 18th century, as ''fei tsui''. Jadeite from the

Motagua Valley The Motagua River () is a river in Guatemala. It rises in the western highlands of Guatemala where it is also called Río Grande, and runs in an easterly direction to the Gulf of Honduras. The final few kilometres of the river form part of the G ...

, was used by the

Olmec The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that t ...

and

Maya peoples The Maya peoples () are an ethnolinguistic group of Indigenous peoples of the Americas, indigenous peoples of Mesoamerica. The ancient Maya civilization was formed by members of this group, and today's Maya are generally descended from people ...

, as well as the indigenous peoples of

Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...

. Unusual colors, like "Olmec blue" jade, which is characterized by its deep blue-green, translucent hue with white flecking, are becoming more highly valued because of its unique beauty and historical use by the Mesoamerican

and also in

Stone Age use

Over 180 axe heads made from jadeitite quarried in northern Italy in the

Neolithic era The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts ...

have been found across the British Isles. Because of the difficulty of working this material, all the axe heads of this type found are thought to have been non-utilitarian and to have represented some form of currency or be the products of gift exchange. A great many jadeite beads and axe heads as well as the remains of jadeite workshops from the

have been uncovered in Itoigawa, Japan. These beads and axes were traded throughout Japan and the Korean Peninsula and were produced by the world's oldest known jadeite-using culture, centered on the Itoigawa region. Maya

References

External links

* {{Gemstones Sodium minerals Aluminium minerals Pyroxene group Monoclinic minerals Minerals in space group 15 Jade