andradite
crystal of African garnet
yellow garnet crystal from Mali
demantoide from Madagascar
crystal of andradite garnet from Africa
watch adorned with demantoid garnets and pearls
color type inclusions, light diffraction
characteristic inclusion ponytail – like in Russian demantoids
characteristic ponytail-like inclusion in russian demantoids
characteristic ponytail-like inclusion in russian demantoids
Detailed sheet
andradite
Andradite: this variety of garnet has been described and identified by Dana, its name is a tribute to a Brazilian mineralogist Jose Bonifacio de Andrada e Silva (1763-1838).
Mélanite : black titanoan variety, its name comes from the Greek “black”.
Topazolite : yellow variety of andradite going from lemon yellow to yellow or brown, transparent, which owes its color to its close to that of topaz.
Demantoid : discovered in the Ural Mountains area of Russia in the mid nineteenth century, this garnet is the most esteemed, a green chromian variety of andradite, whose name comes from the German “Demant” meaning green gem diamond because it has a shining appearance as a diamond, it was highlighted by the famous Russian jeweler Fabergé.
There are so-called “Mali”garnets going from yellow to green, their chemical composition is close to grossular and andradite and they come from Mali. They are called “grandite”, a contraction of grossular and andradite.
CHEMICAL CHARACTERISTICS
Ca3Fe2[SiO4]3
iron and calcium silicate
PHYSICAL CHARACTERISTICS
Main color
black
Other colors
brown, yellow, green
the melanite is black and opaque, the demantoid is green, topazolite is yellow
Color of streak
white
Luster
adamantine, resinous
Hardness
6.5 to 7.5
Density
3.70 to 4.10
Cleavage
indistinct
Fracture
conchoidal, uneven
OPTICAL PROPERTIES
Transparency
translucent, transparent
melanite is black and opaque
Refractive index
1.880 - 1.920
Double refraction
0.000
none, isotropic, sometimes crystals show some polarization anomalies
visible double refraction
No
Dispersion
0,057
Pleochroism
absent
Number of colors
1
isotropic
Absorption spectrum
701 - 640 - 622 - 443
brown andradite spectrum system
demantoide spectrum system
Fluorescence
none
sometimes light pink fluorescence for thetsavorites
Inclusions
bissolithe inclusions and / or of chrysotile (asbestos fiber) into "ponytail" characteristic of the Russian demantoid, other solid inclusions. Areas of color enhanced.
CRYSTALS PROPERTIES
well-formed, often very large, hexakis octahedreon, dodecahedra
crystals system
cubic
OTHER INFORMATIONS
Astrological sign
Capricorn
Month
january
Chinese astrological sign
Rat
APPROACHING GEMS
Exploited
sites
Mélanite: we find this variety of garnet in France (Auvergne), Germany (Baden-Württemberg), United States (Colorado), Italy, Norway, Mali. Topazolite : coming from the USA (California) , Italy (Alps) in Switzerland.
Demantoid : this green garnet comes from Russia (historical deposits in the Urals, inclusions in the typical form of “ponytail”), Italy (Val Malenco), Madagascar where it was discovered in 2009 a new deposit at Ambanja, Namibia (discovered in 1996), Iran, Madagascar, China, Korea, the United States, Zaire.
use in jewelry
Demantoid: popular gem in jewelry because it has a striking appearance, shining like diamonds!
Small size and very expensive, the demantoid gem has been promoted since its discovery by Karl Faberge, goldsmith and jeweler to the Czars, who immediately understood that the exceptional brilliance of this garnet could be put forward in jewelry … at that time was the only green garnet and its only known deposit was in Russia. It can be replaced by green stones with similar effects such as peridot, tourmaline bottle green, emerald.
The name “diamond in Siberia” or “emerald of the Urals” for demantoid garnet is prohibited. The melanite, black variety, was used to make jewelry for mourning, but is not sought.
The garnet is the stone for the anniversary of the second year of marriage.
Daily care
and precautions
Easy to maintain, they can be cleaned very often, insensitive to household products, heat, shock, they are of a proper hardness to be worn as jewels. The Demantoid must be protected from impacts as it is fairly fragile.
imitations and
treatments
The melanite has been imitated by black glass.
improvements
The demantoids of the urals can be heat treated to improve the intensity of their green color.
Historical
healing properties
As its robust and heavy crystals, black andradite strengthens the will, strength, courage, promotes blood circulation, it symbolizes the Yang in China, is an anchor stone. By strengthening the body, the andradite promotes the ability to arbitration, the decision-making in an independent-minded spirit .
The clear yellow or green stones have a beneficial effect on the liver, gallbladder, intestines in relation with the solar plexus chakra. They are a strong source of energy.
Other
Gems
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