Jadeite

Jadeite
	Jadeite from Cloverdale, Mendocino County , California, USA ; Size: 4.5 cm × 3.2 cm × 3 cm
General and classification
chemical formula	NaAl [Si 2 O 6 ]
Mineral class; (and possibly department)	Chain silicates and band silicates
System no. to Strunz ; and to Dana	9.DA.25 ( 8th edition : VIII / F.01) ; 65.01.03c.01
Crystallographic Data
Crystal system	monoclinic
Crystal class ; symbol	monoclinic prismatic; 2 / m
Room group (no.)	C 2 / c (No. 15)
Lattice parameters	a = 9.42 Å ; b = 8.56 Å; c = 5.22 Å ; β = 107.6 °
Formula units	Z = 4
Physical Properties
Mohs hardness	6 to 6.5
Density (g / cm 3 )	3.2 to 3.4
Cleavage	good after {110}
Break ; Tenacity	splintery, brittle
colour	green in all variations to black, rarely white or colorless
Line color	White
transparency	transparent to translucent
shine	freshly broken matt, waxy, sanded glass-like
Crystal optics
Refractive indices	n α = 1.654 to 1.673 ; n β = 1.659 to 1.679 ; n γ = 1.667 to 1.693
Birefringence	δ = 0.013 to 0.020
Optical character	biaxial positive
Axis angle	2V = 70 ° to 80 °
Pleochroism	colorless or green-yellow-green-yellow

Jadeite is a rather seldom occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the monoclinic crystal system with the idealized chemical composition NaAl [Si ₂ O ₆ ]. For natural jadeite However aluminum by low levels of triply positively charged iron - ions have been replaced equivalent ( Diadochie ), so the formula occasionally with Na (Al, Fe ³⁺ ) [Si ₂ O ₆ is specified]. Jadeite can also contain small amounts of calcium and / or magnesium .

As a mono-mineral (predominantly jadeite) rock it is known under the name jade .

Nowadays, jadeite is exclusively processed into gemstones and handicraft objects.

Etymology and history

Jadeite, and thus jade, has been known since the Stone Age and was a highly sought-after mineral in ancient China . However, it did not get its name until the 16th century during the conquest of Mexico by the Spaniards , derived from piedra de ijada due to the healing properties of lumbar and kidney diseases attributed to the stone .

classification

In the meanwhile outdated, but still in use 8th edition of the mineral systematics according to Strunz , the jadeite belonged to the general department of " chain and band silicates (inosilicates) ", where together with aegirine , augite , diopside , esseneit , jervisite , johannsenite , hedenbergite , kanoite , clino , Klinoferrosilit , Kosmochlor , Namansilit , Natalyit , omphacite , Petedunnit , pigeonite and spodumene the subgroup of "clinopyroxene" with the system no. VIII / F.01 within the pyroxene group .

The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also classifies jadeite in the category of “chain and band silicates (inosilicates)”. However, this is further subdivided according to the crystal structure, so that the mineral is classified in the sub-section “Chain and band silicates with 2-periodic single chains Si ₂ O ₆ ; Pyroxene family "can be found, where only together with aegirine, jervisite, cosmochlor, namansilite and natalyite the subgroup" Na-Klinopyroxene, jadeite group "with the system no. 9.DA.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns jadeite to the class of "silicates and Germanates" and there in the department of "chain silicate minerals". Here he is together with Aegirin, Namansilit, Kosmochlor, Natalyit and Jervisit in the group of " C 2 / c Klinopyroxene (Na-Klinopyroxene)" with the system no. 65.01.03c within the sub-section “ Chain Silicates: Simple unbranched chains, W = 1 with chains P = 2 ”.

Crystal structure

Jadeite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 9.42 Å ; b = 8.56 Å; c = 5.22 Å and β = 107.6 ° and 4 formula units per unit cell .

properties

The color of jadeite shows all variations of green and can sometimes play into black. More rarely, colorless, white, yellow, pink to violet, orange or brown jadeite is found, also with small black spots. Jadeite is very tough and resistant, especially if it has a fibrous, matted structure.

Modifications and varieties

Chloromelanite is a mixed crystal made of aegirine, diopside and jadeite with a mixing ratio of about 1: 1: 1. In contrast , nephrite, which is incorrectly attributed to jadeite, is a mixed crystal made of tremolite and actinolite .

Education and Locations

Jadeit formed by high pressure - metamorphosis according to the reaction equations

Albite (NaAlSi ₃ O ₈ ) jadeite (NaAlSi ₂ O ₆ ) + quartz (SiO ₂ ) ${\ displaystyle \ Longleftrightarrow}$

Nepheline ((Na, K) [AlSiO ₄ ]) + albite (NaAlSi ₃ O ₈ ) 2 jadeite (NaAlSi ₂ O ₆ ) ${\ displaystyle \ Longleftrightarrow}$

in blue slate , metamorphically embossed greywacke and so-called jadeite gneiss . However, it is preferably formed in the lower pressure or temperature range together with diopside and aegirine at pressures of 7 to 11 kbar and temperatures between 250 and 400 ° C. Rocks containing jadeite are mainly found in the subduction zones at continental borders. Feldspar rarely occurs in nature as pure albite, so an anorthite component and the presence of calcium (Ca) can always be assumed. Lawsonite is also involved in the transition from feldspar to jadeite mentioned : feldspar = jadeite + lawsonite + quartz.

Find locations include Minas Gerais in Brazil , various provinces of the People's Republic of China , Forchheim in Germany , the Cyclades archipelago in Greece , Grenville and Labrador in Canada , Tawmaw in Myanmar, Ben Sur in the USA , Itoigawa in Japan (there together with Itoigawait and Rengeit ) - others are in New Zealand and Tibet .

In 1992, the French archaeologist Pierre Pétrequin and his wife discovered traces of systematic mining on jadeite by Neolithic people in the high mountains of Monte Viso in Piedmont and on Monte Beigua in Liguria . Also in meteorites such as B. in the meteorite of Chelyabinsk jadeite could be found.

use

Jadeite mask of the Olmecs

In the early Neolithic , sharp-nosed axes were made from alpine jadeite , presumably using sawing technology. The origin of the material is on Monte Viso in the western Alps. The jadeite axes were widely traded and reached as far as Brittany and Great Britain ( sweet-track jade). In its unprocessed form, jadeite appears rather inconspicuous. The object is only given an extremely smooth and sometimes even translucent surface by grinding. Some of the axes are so large that they are considered prestige items.

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

Esoteric

Jadeite is believed to have healing properties for kidney problems.

literature

Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology. 7th completely revised and updated edition. Springer Verlag, Berlin a. a. 2005, ISBN 3-540-23812-3 .
Walter Schumann: Precious stones and gemstones . 13th edition. BLV, Munich 2002, ISBN 3-405-16332-3
Edition Dörfler: Minerals Encyclopedia . Nebel Verlag, ISBN 3-89555-076-0

Web links

Commons : Jadeite - collection of images, videos and audio files

Wiktionary: Jadeite - explanations of meanings, word origins, synonyms, translations

Mineral Atlas: Jadeite (Wiki)
Mineral Lexicon - Jadeite
Webmineral - Jadeite (Engl.)
Stone Age status symbols
Conference on Jadeite in Neolithic Europe (PDF file; 746 kB)

Individual evidence

↑ ^a ^b ^c ^d ^e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 621 .
↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 525 .
↑ The product of a cosmic collision ( Memento from March 4, 2016 in the Internet Archive ) orf.at
↑ Jadeite in Chelyabinsk meteorite and the nature of an impact event on its parent body nature.com, accessed on May 23, 2014
↑ P. Pétrequin, M. Errera, AM Pétrequin and P. Allard, The neolithic quarries of Mont Viso (Piedmont, Italy). Initial radiocarbon dates. European Journal of Archeology 9 (1), 2006, pp. 7-30
↑ State Office for the Preservation of Monuments and Archeology Saxony-Anhalt - January: A 6000 year old symbol of power

[StrunzNickel-1] Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 621 .

[Lapis-2] Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .

[Rösler-3] Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 525 .

[4] The product of a cosmic collision ( Memento from March 4, 2016 in the Internet Archive ) orf.at

[5] Jadeite in Chelyabinsk meteorite and the nature of an impact event on its parent body nature.com, accessed on May 23, 2014

[Pétrequin-6] P. Pétrequin, M. Errera, AM Pétrequin and P. Allard, The neolithic quarries of Mont Viso (Piedmont, Italy). Initial radiocarbon dates. European Journal of Archeology 9 (1), 2006, pp. 7-30

[lda-lsa.de-7] State Office for the Preservation of Monuments and Archeology Saxony-Anhalt - January: A 6000 year old symbol of power