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A n d r a d i t e ●
A r t i c l e ●
T a l k ●
L a n g u a g e
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( R e d i r e c t e d f r o m M e l a n i t e )
Single crystal (4.2 cm ) – Diakon, Nioro du Sahel Circle, Kayes Region, Mali
Garnet group
Ca 3 Fe 2 4 3
Adr[1 ]
9.AD.25
Cubic
Hexoctahedral (m 3 m ) H-M symbol : (4/m 3
I a 3 d
a = 12.056 Å; Z = 8
Yellow, greenish yellow to emerald-green, dark green; brown, brownish red, brownish yellow; grayish black, black; may be sectored
Commonly well-crystallized dodecahedra, trapezohedra, or combinations, also granular to massive
none
conchoidal to uneven
Brittle
6.5 to 7
Adamantine to resinous, dull
White
Transparent to translucent
3.859 calculated; 3.8–3.9 measured
Isotropic, typically weakly anisotropic
n = 1.887
demantoid – 440 nm band or complete absorption at 440 nm and below, may also have lines at 618, 634, 685, 690 nm [2 ]
[2 ] [3 ] [4 ] [5 ]
transparent light to dark green to yellow-green
opaque black
transparent to translucent yellow, may show chatoyancy
Andradite includes three varieties:
Colophonite [6 ] : 61
Demantoid gemological world.[7 ]
Melanite : Black in color due to limited substitution of titanium for iron. Also known as "titanian andradite". Forms a solid solution with morimotoite and schorlomite depending on titanium and iron content.[8 ]
Topazolite : Yellow-green in color and sometimes of high enough quality to be cut into a faceted gemstone , it is rarer than demantoid.[7 ]
It was first described in 1868 for an occurrence in Drammen , Buskerud , Norway .[3 ] [4 ] [7 ] Brazilian statesman, naturalist, professor and poet José Bonifácio de Andrada e Silva (1763–1838).[3 ] [7 ]
Occurrence
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It occurs in skarns developed in contact metamorphosed impure limestones or calcic igneous rocks ; in chlorite schists and serpentinites and in alkalic igneous rocks (typically titaniferous ). Associated minerals include vesuvianite , chlorite , epidote , spinel , calcite , dolomite and magnetite .[3 ] Iran , Italy , the Ural Mountains of Russia , Arizona and California and in Dnipropetrovsk Oblast in Ukraine .
Like the other garnets, andradite crystallizes in the cubic space group [[Ia 3 d ]], with unit-cell parameter of 12.051 Å at 100 K.[9 ]
The spin structure of andradite contains two mutually canted equivalent antiferromagnetic sublattices[10 ] Néel temperature (T N [11 ]
See also
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References
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^ a b Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
^ a b c d Handbook of Mineralogy
^ a b Andradite , Mindat.org
^ Webmineral data
^ Olga Bortnik . All about precious stones. ― Moscow: Harvest, 2011.
^ a b c d Grande, Lance; Augustyn, Allison (2009). Gems and Gemstones: Timeless Natural Beauty of the Mineral World ISBN 978-0-226-30511-0
^ Melanite , Mindat.org
^ Thomas Armbruster and Charles A. Geiger (1993): "Andradite crystal chemistry, dynamic X-site disorder and structural strain in silicate garnets ." European Journal of Mineralogy v. 5, no. 1, p. 59-71.
^ Danylo Zherebetskyy (2010). Quantum mechanical first principles calculations of the electronic and magnetic structure of Fe-bearing rock-forming silicates Universal Publishers /Dissertation.com, Boca Raton, Florida, USA, p. 136. ISBN 1-59942-316-2 .
^ Enver Murad (1984): "Magnetic ordering in andradite ." American Mineralogist 69, no. 7-8; pp. 722–24.
External links
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Andradite at Wikimedia Commons
R e t r i e v e d f r o m " https://en.wikipedia.org/w/index.php?title=Andradite&oldid=1222194696 "
L a s t e d i t e d o n 4 M a y 2 0 2 4 , a t 1 4 : 0 9 L a n g u a g e s
● ا ل ع ر ب ي ة ● A s t u r i a n u ● A z ə r b a y c a n c a ● Б е л а р у с к а я ● Б е л а р у с к а я ( т а р а ш к е в і ц а ) ● Б ъ л г а р с к и ● C a t a l à ● Č e š t i n a ● D e u t s c h ● Ε λ λ η ν ι κ ά ● E s p a ñ o l ● E u s k a r a ● ف ا ر س ی ● F r a n ç a i s ● I t a l i a n o ● ע ב ר י ת ● Қ а з а қ ш а ● L i e t u v i ų ● M a g y a r ● N e d e r l a n d s ● 日 本 語 ● N o r s k n y n o r s k ● O ʻ z b e k c h a / ў з б е к ч а ● P o l s k i ● P o r t u g u ê s ● Р у с с к и й ● S l o v e n š č i n a ● S v e n s k a ● Т о ҷ и к ӣ ● У к р а ї н с ь к а ● 中 文
● T h i s p a g e w a s l a s t e d i t e d o n 4 M a y 2 0 2 4 , a t 1 4 : 0 9 ( U T C ) . ● C o n t e n t i s a v a i l a b l e u n d e r C C B Y - S A 4 . 0 u n l e s s o t h e r w i s e n o t e d . ● P r i v a c y p o l i c y ● A b o u t W i k i p e d i a ● D i s c l a i m e r s ● C o n t a c t W i k i p e d i a ● C o d e o f C o n d u c t ● D e v e l o p e r s ● S t a t i s t i c s ● C o o k i e s t a t e m e n t ● T e r m s o f U s e ● D e s k t o p
Media related to Andradite at Wikimedia Commons