Mineral Type - Garnet Group

The classical name for a group of silicate minerals with the same structure. Not to be confused with the garnet structural group which on Mindat is defined as a larger group of minerals with the same type of crystal structure as that of the classical garnet minerals, but including minerals that are not silicates.

Name

Named Carchedonius Garamanticus = Carthaginian or Garamantic Carbuncle in 77-79 by Pliny the Elder. Earlier named ΑνθραϪέ by Tyrtamus, commonly known by his honorary name, Theophrastus, possibly about 325-300 BCE, but seemingly a name also used for ruby spinel and red-pink sapphires. Named from granatum (a pomegranate) for its resemblance to seeds of this fruit.

Chemical Properties

Formula: X3Z2(SiO4)3

X = Ca, Fe, etc.
Z = Al, Cr, etc.

Age Distribution

Recorded ages: Neoarchean to Neogene : 2640 ± 11 Ma to 5 Ma - based on 5 recorded ages

Varieties

Traditional garnet species :
Almandine Fe2+3Al2(SiO4)3,
Pyrope Mg3Al2(SiO4)3,
Spessartine Mn2+3Al2(SiO4)3,
Andradite Ca3Fe3+2(SiO4)3,
Grossular Ca3Al2(SiO4)3, and
Uvarovite Ca3Cr2(SiO4)3