Jadeite

Jadeite is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the monoclinic crystal system with the idealized chemical composition NaAl [ Si2O6 ]. For natural Jadeiten However, aluminum can by small amounts of triply positively charged iron ions equivalently replaced his ( Diadochie ), so the formula is also sometimes listed with Na (Al, Fe3 ) [ Si2O6 ]. Even small amounts of calcium and / or magnesium may be included in jadeite.

As mono- mineral ( mainly from existing jadeite ) rock it is known under the name Jade.

Jadeite is nowadays processed for precious stones and decorative arts objects.

Special Features

The color of the jadeite shows all variations of green and can sometimes play the mark. Rare is also colorless, white, yellow, pink to violet found, orange or brown jadeite, with small black spots. Jadeite is very tough and resistant, especially in fibrous, matted structure.

Etymology and history

Jadeite Jade and therefore has been known since the Stone Age and was in ancient China, a highly sought after mineral. It was named, however, until the 16th century during the conquest of Mexico by the Spaniards, derived from piedra de ijada because of the stone ascribed healing effects on lumbar and kidney disease.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the jadeite belonged to the general ward of the " chains and chain silicates ( inosilicates ) ", where he, together with aegirine, augite, diopside, Esseneit, Jervisit, Johannsenite, hedenbergite Kanoit, Klinoenstatit, Klinoferrosilit, Kosmochlor, Namansilit, Natalyit, omphacite, Petedunnit, pigeonite and spodumene the subgroup of " clinopyroxene " with the system no. VIII/F.01 formed within the pyroxene group.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the jadeite also included in the department's " chain and chain silicates ( inosilicates ) ". However, this is further subdivided according to the crystal structure, so that the mineral according to its construction in the subsection " chain and chain silicates with 2- periodic single chains Si2O6; Pyroxene family " is to find where it only together with aegirine, Jervisit, Kosmochlor, Namansilit and Natalyit the subgroup ". Na - clinopyroxene, Jadeitgruppe "with the system no 9.DA.25 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the jadeite in the class of " silicates and Germanates " and there in the department of " chain silicate minerals " one. Here he is with aegirine, Namansilit, Kosmochlor, Natalyit and Jervisit in the group of " C2 / c clinopyroxene (Na - clinopyroxene ) " with the system no. 65.01.03c within the subdivision " chain silicates: Simple unbranched chains, W = 1 with chains P = 2" to find.

Varieties

Chloromelanite is a mixed crystal of aegirine, diopside and jadeite with the mixing ratio of about 1:1:1. The erroneously attributed to the jadeite jade is, however, a mixed crystal of tremolite and actinolite.

Education and Locations

Jadeite is formed by high -pressure metamorphism on the reaction equations

  • Albite ( NaAlSi3O8 ) jadeite ( NaAlSi2O6 ) quartz ( SiO2)
  • Nepheline ( (Na, K) [ AlSiO4 ] ) albite ( NaAlSi3O8 ) 2 jadeite ( NaAlSi2O6 )

Blue shale, metamorphic overprinted greywacke and so-called jadeite gneisses. However, it is formed preferably in the lower pressure and temperature, together with diopside Aegirin and at pressures 7-11 kbar and temperatures of between 250 and 400 ° C. Jadeithaltige rocks are therefore mainly found in subduction zones at continental borders. Feldspar occurs in nature only rarely as pure albite before, so a anorthite component and the presence of calcium (Ca) is always assumed. When called transition from feldspar to jadeite and lawsonite is accordingly involved: feldspar = jadeite lawsonite quartz.

Locations include Minas Gerais in Brazil, various provinces of the People's Republic of China, Forchheim in Germany, the Cyclades group of islands in Greece, Grenville and Labrador in Canada, Tawmaw / Myanmar in New Zealand, Tibet, China, and Ben Sur in the U.S.

In the high mountain ranges of Mount Viso in Piedmont and Monte Beigua in Liguria, the French archaeologist Pierre Pétrequin and his wife in 1992 discovered the traces of systematic mining on Jadeitit by Neolithic people.

Crystal structure

Jadeite crystallized in the monoclinic space group C2 / c ( Raumgruppen-Nr. 15) with the lattice parameters a = 9.42 Å; b = 8.56 Å; c = 5.22 Å and 107.6 ° and β = 4 formula units per unit cell.

Use

In the Neolithic pointed necked hatchets were made of Alpine jadeite, presumably in sawing technology. The area of ​​origin of the material is located on Monte Viso in the Western Alps. The Jadeitbeile were traded far and came to Brittany and Great Britain (Sweet -track jade). In their raw form jadeite appears rather unimpressive. Only by grinding the object is assigned a very smooth and sometimes even translucent surface. Some of the axes are so large that they can be addressed as prestige items.

Already between the 10th and 6th centuries BC, the Olmecs carved jade their face masks.

Esoteric

Jadeite is a kidney ailments attributed curative effect.

425047
de