Composition: The Garnet Group consists of two Isomorphic series, The Pyralspite and The Ugrandite series.
Pyralspite Series:
Almandine: Fe
3Al2(SiO4)3
Pyrope: Mg3Al2(SiO4)3
Spessartite: Mn3Al2(SiO4)3
Ugrandite: Series:
Andradite: Ca
3Fe2(SiO4)3
Grossular: Ca3Al2(SiO4)3
Uvarovite: Ca3Cr2)SiO4)3
crystal System:
Cubic
Habit:
Dodecahedral, Icositetrahedral is less common
Refractive Index:
different for each variety
Almandine: 1.76-1.81
Andradite: 1.89
Grossular: 1.74-1.75
Pyrope: 1.74-1.75
Spessartite: 1.8-1.82
Uvarovite: 1.87

Dispersion: different for each variety
Almandine: 0.024
Andradite: 0.057
Grossular: 0.028
Pyrope: 0.022
Spessartite: 0.027
Uvarovite: 0.030
Specific Gravity:
different for each variety
Almandine: 3.8-4.2
Andradite: 3.85
Grossular: 3.6-3.7
Pyrope: 3.7-3.8
Spessartite: 4.16
Uvarovite: 3.77
Hardness: different for each variety
Almandine: 7.5
Andradite: 6.5
Grossular: 7.0-7.5
Pyrope :7.25
Spessartite: 7.25
Uvarovite: 7.5
Fracture: Subconchoidal
Lustre: Vitreous to Sub-Adamantine
Absorption Spectrum: To follow it's complex
Inclusions: Almandine- crystals and associated stress cracks,rutlie, Demantoid- "Horsetail" radiation Byssolite fibes. Grossular- profusion of small crystals of Apatite and or Zircon wihich gives a treacly appearance. Pyrope- Occasional needle like crystals. spessartite -Shredded looking feathers
Occurrence: different for each variety
Almandine: Austria, Brazil, China, Czechoslovakia, Sri Lanka
Andradite: Switzerland (Yellow), USSR (Demantoid)
Grossular: Brazil, Canada,Kenya (Tsavorite), New Zealand, Soth Africa, Sri Lanka (Especially the Hessonite variety)Tanzania (Tsavorite) USA
Pyrope: Czechoslovakia, South Africa, Sri Lanka, USA, USSR
Spessartite: Brazil, Malagasy Republic, Mayanmar (Burma), Sri Lanka, USA
Uvarovite: Canada, Finland, Poland, USA, USSR

Garnet

John Cadby Jewellers
 Goldsmith, Silversmith,
Diamond Merchants, Appraiser & Engraver.
**************************************************************************
3, White Hart Yard, Trowbridge, Wiltshire.  BA14 8BY
Tel: 01225 776322  E-Mail: John@Cadby.co.uk

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