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Andradite

Andradite is a species of the garnet group. It was named after José Bonifácio de Andrada e Silva (1763-1838), Brazilian politician and mineralogist.

The most valuable variety of andradite is demantoid, also called Uralian emerald. What makes it special are inclusions of actinolite, referred to as horsetail inclusions because of the white or golden color and thread-like shape.[1]

Andradite

Basic properties

CompositionCa3Fe2(SiO4)3
ClassSilicates (Neosilicates)
Crystal systemCubic
Mohs' hardness6,5-7
FractureConchoidal
CleavageNone
LustreGlassy to adamantine
StreakWhite
LocalitiesRussia, Italy, Switzerland, USA, China, Namibia

References

  1. ↑ Minerały i kamienie szlachetne by RBA Collecionables, S.A., ISBN 978-83-7813-150-2, 2012.
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