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40-447: Jadeite is a pyroxene mineral with composition Na Al Si 2 O 6 . It is hard ( Mohs hardness 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 the subduction zones of continental margins, where rock undergoes metamorphism at high pressure but relatively low temperature. Jadeite

80-402: A miscibility gap between pigeonite and augite compositions. There is an arbitrary separation between augite and the diopside-hedenbergite ( CaMgSi 2 O 6   CaFeSi 2 O 6 ) solid solution. The divide is taken at >45 mol.% Ca. As the calcium ion cannot occupy the Y site, pyroxenes with more than 50 mol.% calcium are not possible. A related mineral wollastonite has

120-458: A semi-precious stone . Green diopside crystals included within a white feldspar matrix are also sold as gemstones, usually as beads or cabochons. This stone is often marketed as 'green spot jasper' or green spot stone'. Violane is a manganese -rich variety of diopside, violet to light blue in color. Diopside derives its name from the Greek dis , "twice", and òpsè , "face" in reference to

160-410: A charge of +1, into the pyroxene implies the need for a mechanism to make up the "missing" positive charge. In jadeite and aegirine this is added by the inclusion of a +3 cation (aluminium and iron(III) respectively) on the Y site. Sodium pyroxenes with more than 20 mol.% calcium, magnesium or iron(II) components are known as omphacite and aegirine-augite . With 80% or more of these components

200-455: 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 NaAlSi 2 O 6 and has the typical clinopyroxene structure. This consists of long chains of silica tetrahedra in which each silicon ion

240-661: A pressure of 10 to 25 kbar and a temperature of 600 to 1,000 °C (1,100 to 1,800 °F) via the reaction: Jadeite can also form at high pressure via the reaction: At still higher pressure, corresponding to the highest blueschist facies , jadeite reacts with lawsonite to form zoisite and paragonite : Minerals associated with jadeite include: glaucophane , lawsonite , muscovite , aragonite , serpentine and quartz . Rocks that consist almost entirely of jadeite are called jadeitite . In all well-documented occurrences, jadeitite appears to have formed from subduction zone fluids in association with serpentinite . Jadeitite

280-403: Is a miscibility gap between diopside and pigeonite , and at lower temperatures, between diopside and orthopyroxene . The calcium /(calcium+ magnesium + iron ) ratio in diopside that formed with one of these other two pyroxenes is particularly sensitive to temperature above 900 °C, and compositions of diopside in peridotite xenoliths have been important in reconstructions of temperatures in

320-499: Is a precursor of chrysotile (white asbestos ) by hydrothermal alteration and magmatic differentiation ; it can react with hydrous solutions of magnesium and chlorine to yield chrysotile by heating at 600 °C for three days. Some vermiculite deposits, most notably those in Libby, Montana , are contaminated with chrysotile (as well as other forms of asbestos) that formed from diopside. At relatively high temperatures, there

360-421: Is also a rare parting on [100]. The interlocking crystals of massive jadeite help give it its extreme toughness. Jadeite has a Mohs hardness of 6.5 to 7, slightly less than that of common quartz . Fracture surfaces are sugary in texture, and sparkle from the exposed perfect cleavage on [110]. Jade is relatively dense, with a specific gravity of 3.3 to 3.5 in natural specimens. The specific gravity increases with

400-645: 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 Myanmar , the Alps, Russia, California, Japan, and Guatemala . In the Franciscan Complex of California, jadeite is associated with glaucophane, aragonite, muscovite, lawsonite, and quartz. However, occurrences of lapidary quality are almost exclusive to Myanmar . Stream boulders of

440-507: Is found in ultramafic ( kimberlite and peridotite ) igneous rocks , and diopside-rich augite is common in mafic rocks, such as olivine basalt and andesite . Diopside is also found in a variety of metamorphic rocks, such as in contact metamorphosed skarns developed from high silica dolomites . It is an important mineral in the Earth 's mantle and is common in peridotite xenoliths erupted in kimberlite and alkali basalt. Diopside

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480-460: Is found in two forms: black star diopside and chrome diopside (which includes chromium , giving it a rich green color). At 5.5–6.5 on the Mohs scale , chrome diopside is relatively soft to scratch. Due to the deep green color of the gem, they are sometimes referred to as Siberian emeralds, although they are on a gemological level completely unrelated, emerald being a precious stone and diopside being

520-412: Is intermediate in composition between jadeite and diopside . However, there is not a true solid solution 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 . Chloromelanite is a dark green variety of jadeite in which some aluminium is replaced by iron, while imperial jade ,

560-403: 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. Jadeite's color commonly ranges from white through pale apple green to deep jade green but can also be blue-green (like

600-445: 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 (occupying 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

640-474: 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 . 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 . The name jadeite is derived (via French : jade and Latin : ilia ) from

680-528: The Earth's mantle . Chrome diopside ( (Ca,Na,Mg,Fe,Cr) 2 (Si,Al) 2 O 6 ) is a common constituent of peridotite xenoliths, and dispersed grains are found near kimberlite pipes, and as such are a prospecting indicator for diamonds . Occurrences are reported in Canada , South Africa , Russia , Brazil , and a wide variety of other locations. In the US, chromian diopside localities are described in

720-656: The Neolithic era 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 Neolithic era have been uncovered in Itoigawa, Japan . These beads and axes were traded throughout Japan and

760-798: The Spanish phrase "piedra de ijada" which means "stone of the side". The Latin version of the name, lapis nephriticus , is the origin of the term nephrite , which is a different mineral that also shares the common name jade . Jadeite is a hard, extremely tough, rare mineral of the clinopyroxene 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 in massive jadeite. Crystals are four-sided or eight-sided in cross section and show perfect cleavage on [110] at angles of 87 and 93 degrees. There

800-462: The Uyu River remain an important source of jadeite. 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

840-421: The monoclinic prismatic class. It has two distinct prismatic cleavages at 87 and 93° typical of the pyroxene series. It has a Mohs hardness of six, a Vickers hardness of 7.7 GPa at a load of 0.98 N, and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of n α =1.663–1.699, n β =1.671–1.705, and n γ =1.693–1.728. The optic angle is 58° to 63°. Diopside

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880-402: The monoclinic system , with space group C2/c . Pure jadeite has the composition NaAlSi 2 O 6 . There is no significant replacement of silicon by aluminium in natural jadeite, and only very limited substitution of ferric iron for aluminium. However, calcium substitutes for up to 20% of the sodium, balanced by substitution of magnesium or ferrous iron for aluminium. Omphacite

920-416: The pyroxenoids , are much less common.) Their structure consists of parallel chains of negatively-charged silica tetrahedra bonded together by metal cations. In other words, each silicon ion in a pyroxene crystal is surrounded by four oxygen ions forming a tetrahedron around the relatively small silicon ion. Each silicon ion shares two oxygen ions with neighboring silicon ions in the chain. The tetrahedra in

960-444: 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. Significant occurrences of jadeite are isolated and rare. It

1000-975: The serpentinite belt in northern California, in kimberlite in the Colorado-Wyoming State Line district, in kimberlite in the Iron Mountain district, Wyoming, in lamprophyre at Cedar Mountain in Wyoming, and in numerous anthills and outcrops of the Tertiary Bishop Conglomerate in the Green River Basin of Wyoming. Much chromian diopside from the Green River Basin localities and several of the State Line Kimberlites have been gem in character. Gemstone quality diopside

1040-604: The Korean Peninsula and were produced by the world's oldest known jadeite-using culture, centered on the Itoigawa region. Pyroxene The name pyroxene is derived from the Ancient Greek words for 'fire' ( πυρ , pur ) and 'stranger' ( ξένος , xénos ). Pyroxenes were so named due to their presence in volcanic lavas , where they are sometimes found as crystals embedded in volcanic glass ; it

1080-603: The Y site and bulkier ions on the X site. Not all the resulting mechanisms to achieve charge neutrality follow the sodium example above, and there are several alternative schemes: In nature, more than one substitution may be found in the same mineral. Diopside Diopside is a monoclinic pyroxene mineral with composition MgCaSi 2 O 6 . It forms complete solid solution series with hedenbergite ( FeCaSi 2 O 6 ) and augite , and partial solid solutions with orthopyroxene and pigeonite . It forms variably colored, but typically dull green crystals in

1120-486: The chain all face in the same direction, so that two oxygen ions are located on one face of the chain for every oxygen ion on the other face of the chain. The oxygen ions on the narrower face are described as apical oxygen ions. Pairs of chains are bound together on their apical sides by Y cations, with each Y cation surrounded by six oxygen ions. The resulting pairs of single chains have sometimes been likened to I-beams . The I-beams interlock, with additional X cations bonding

1160-605: The chemical species occupying the X (or M2) site, the Y (or M1) site, and the tetrahedral T site. Cations in Y (M1) site are closely bound to 6 oxygens in octahedral coordination. Cations in the X (M2) site can be coordinated with 6 to 8 oxygen atoms, depending on the cation size. Twenty mineral names are recognised by the International Mineralogical Association's Commission on New Minerals and Mineral Names and 105 previously used names have been discarded. A typical pyroxene has mostly silicon in

1200-760: The end of the 18th century, as fei tsui . Jadeite from the Motagua Valley , Guatemala , was used by the Olmec and Maya peoples , as well as the indigenous peoples of Costa Rica . 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 Olmec and also in Costa Rica . Over 180 axe heads made from jadeitite quarried in northern Italy in

1240-425: The ferrosilite equivalents). Increasing the calcium content prevents the formation of the orthorhombic phases and pigeonite ( [Mg,Fe,Ca][Mg,Fe]Si 2 O 6 ) only crystallises in the monoclinic system. There is not complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol.% are not stable with respect to a pair of exolved crystals. This leads to

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1280-459: The formula of the hypothetical calcium end member ( Ca 2 Si 2 O 6 ) but important structural differences mean that it is instead classified as a pyroxenoid. Magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of pyroxene minerals are the sodium-rich pyroxenes, corresponding to the 'pyroxene triangle' nomenclature. The inclusion of sodium, which has

1320-494: 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 nephrite by its vitreous luster on polished surfaces (polished nephrite has an oily luster) and by its higher density and refractive index . Serpentine also has

1360-427: The most valuable variety of jade, is colored an intense emerald green by traces of chromium . Jadeite occurs with albite in metamorphic rock of the low-temperature, high-pressure blueschist facies at destructive plate margins . Although it is intermediate in silica content between albite and nepheline , it is not stable under the conditions in which these two minerals are present. Formation of jadeite requires

1400-486: The outer faces of the I-beams to neighboring I-beams and providing the remaining charge balance. This binding is relatively weak and gives pyroxenes their characteristic cleavage . The chain silicate structure of the pyroxenes offers much flexibility in the incorporation of various cations and the names of the pyroxene minerals are primarily defined by their chemical composition. Pyroxene minerals are named according to

1440-419: The pyroxene is classified using the quadrilateral diagram. A wide range of other cations that can be accommodated in the different sites of pyroxene structures. In assigning ions to sites, the basic rule is to work from left to right in this table, first assigning all silicon to the T site and then filling the site with the remaining aluminium and finally iron(III); extra aluminium or iron can be accommodated in

1480-514: The tetrahedral site and predominately ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT 2 O 6 . The names of the common calcium–iron–magnesium pyroxenes are defined in the 'pyroxene quadrilateral'. The enstatite-ferrosilite series ( [Mg,Fe]SiO 3 ) includes the common rock-forming mineral hypersthene , contains up to 5 mol.% calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite (and

1520-472: The two ways of orienting the vertical prism . Diopside was discovered and first described about 1800, by Brazilian naturalist Jose Bonifacio de Andrada e Silva . Diopside based ceramics and glass-ceramics have potential applications in various technological areas. A diopside based glass-ceramic named 'silceram' was produced by scientists from Imperial College, UK during the 1980s from blast furnace slag and other waste products. They also produced glass-ceramic

1560-479: Was assumed they were impurities in the glass, hence the name meaning "fire stranger". However, they are simply early-forming minerals that crystallized before the lava erupted. The upper mantle of Earth is composed mainly of olivine and pyroxene minerals. Pyroxene and feldspar are the major minerals in basalt , andesite , and gabbro rocks. Pyroxenes are the most common single-chain silicate minerals. (The only other important group of single-chain silicates,

1600-520: Was once thought to cure kidney ailments when applied to the side of the body. Jadeite is one of two minerals recognized as the gemstone jade . The other is nephrite . Occasionally, other minerals such as serpentine or quartz 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 as of 1994. Jadeite jade first came into significant use in China only towards

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