Jadeite is a pyroxene mineral with composition NaAlSi2O6. 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 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 jade and ilia) from 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 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 the iron content, and very pure jadeite has a specific gravity of 3.25.
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Hardstone carving, in art history and archaeology, is the artistic carving of semi-precious stones (and sometimes gemstones), such as jade, rock crystal (clear quartz), agate, onyx, jasper, serpentinite, or carnelian, and for objects made in this way. Normally the objects are small, and the category overlaps with both jewellery and sculpture. Hardstone carving is sometimes referred to by the Italian term pietre dure; however, pietra dura (with an "a") is the common term used for stone inlay work, which causes some confusion.
The Maya civilization (ˈmaɪə) was a Mesoamerican civilization that existed from antiquity to the early modern period. It is known by its ancient temples and glyphs (script). The Maya script is the most sophisticated and highly developed writing system in the pre-Columbian Americas. The civilization is also noted for its art, architecture, mathematics, calendar, and astronomical system. The Maya civilization developed in the Maya Region, an area that today comprises southeastern Mexico, all of Guatemala and Belize, and the western portions of Honduras and El Salvador.
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years.
In this work, we attempt to simulate residual stresses and springback of a deformed metal pan based on a micro-macro modelling of the elastic and plastic strains. Samples cut out of an aluminium plate, under different angles relative to the rolling directi ...
2003
Using the CRPG-CNRS Cameca 1270 ion microprobe facility, we have measured boron isotopic compositions (B-11/B-10) in different ultrastructural components of the deep-sea aragonitic scleractinian coral Lophelia pertusa. We observe a systematic difference in ...
Stromatolites have been extensively used as indicators of ancient life on Earth. Although much work has been done on modern stromatolites, the extent to which biological processes control their structure, and the respective contributions of biological and ...