Supergroup, species and gem varieties
Pyrope, almandine, grossular, spessartine, andradite and uvarovite are species/end members. Tsavorite and hessonite belong to grossular; demantoid to andradite; rhodolite is a compositional trade variety.
Keep each chapter’s scientific identity: a family, species, variety, trade label, rock and fossil are different kinds of names.
Mineral species
Almandine is a familiar iron-rich member of the garnet group. Dark rough and a well-lit cut gem can look surprisingly different, especially when a thick stone absorbs much of the light.
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Mineral variety
Tsavorite is a green gem variety of grossular garnet. Its vivid color can resemble other green gems, while the mineral identity remains distinct.
Robert M. Lavinsky · CC BY-SA 3.0 · Display crop
Mineral species
Grossular is a calcium aluminum garnet species with a wide color range. Green, orange, pale and nearly colorless examples help show why garnet cannot be defined as a red stone.
Robert M. Lavinsky · CC BY-SA 3.0 · Display crop
Mineral variety
Hessonite is an orange to brownish gem variety of grossular garnet. Its warm palette works in both cut gems and rounded beads.
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Mineral species
Spessartine is a manganese aluminum garnet species. Orange is familiar in gem material, while darker red and brown specimens also occur.
Géry PARENT · Public domain · Display crop
Mineral species
Andradite is a calcium iron garnet species, sometimes brown, green or nearly black. Its special gem varieties are part of a wider mineral story.
Didier Descouens · CC BY-SA 4.0 · Display crop
Mineral variety
Demantoid is the green gem variety of andradite garnet. A cut gem can show lively dispersion, but its appearance should not be confused with diamond identity.
Robert M. Lavinsky · CC BY-SA 3.0 · Display crop
Gem material
Rhodolite is a red-purple gem trade variety in the pyrope–almandine garnet series. Its inviting color can range from pinkish red to a deeper raspberry shade.
Darla Sondrol · CC0 1.0 · Display crop
Mineral species
Pyrope is the magnesium-aluminum garnet end member. Natural garnets commonly contain solid-solution components; red appearance is not a chemical analysis.
Robert M. Lavinsky · CC BY-SA 3.0 · Display crop
Mineral species
Uvarovite is calcium-chromium garnet. Green tsavorite is a grossular variety, and demantoid is an andradite variety; neither should be renamed uvarovite just because it is green.
Géry PARENT · CC BY-SA 4.0 · Display crop