Andradite
Andradite,
like other garnets, forms rounded crystals with 12 rhombic or 24
trapezoidal faces or combinations of these and some other forms. This
crystal habit is classic for the garnet minerals. Andradite is the
calcium iron garnet and forms in contact or regional metamorphic
enviroments as does grossular, the calcium aluminum garnet. It is
believed that these garnets form from the metamorphism of impure
siliceous limestones.
Andradite has many varieties based on
color.
- Melanite
is the black variety.
- Demantoid
is the bright green variety and is sometimes cut as a gem.
- Topazolite
is the yellow variety and is also occassionally cut as a gem.
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