ALMANDINE

The Garnet
Group of
Minerals


GROSSULAR

ANDRADITE


RASBERRY GARNET
a variety of
GROSSULAR


UVAROVITE


GROSSULAR
on DIOPSIDE


MELANITE
a variety of
ANDRADITE


SPESSARTINE

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For natural garnet mineral specimens, select any of the mineral names above.

For Garnet Jewelry, see --> GARNET JEWELRY

Garnets as a group are relatively common in highly metamorphosed rocks and in some igneous formations. They form under the high temperatures and/or pressures that those types of rocks must endure. Garnets can be used by geologists as a gauge of how much temperature and pressure the rock has endured. As a gemstone, garnets have had a mixed reputation. Garnets do possess high indices of refraction, are hard enough, have pretty colors, are wonderfully transparent, lack cleavage and are durable; thus making good candidates for gemstones. However, many people consider garnets to be inferior to other colored gems. This may be due to garnet's relative abundance and widespread use, and therefore a (typically) low price. Garnets are greatly variable in colors and varieties, though, and many of these are both rare and beautiful, producing genuinely precious gemstones. Some garnets are truly unique in the mineral kingdom and have much to offer as both gemstones and mineral specimens. Of course, garnets are the January Birthstone.

The general formula for most of the garnets is A3B2(SiO4)3. The A represents divalent metals such as calcium, iron, magnesium and/or manganese. The B represents trivalent metals such as aluminum, chromium, iron and/or manganese and in the rarer garnets; vanadium, titanium, zirconium and/or silicon. The general formula for a couple of rarer garnets (hibschite and katoite) is A3B2(SiO4)3-X(OH)4X. The main differences in physical properties among the members of the garnet group are slight variations in color, density and index of refraction.

Garnets are isostructural, meaning that they share the same crystal structure. This leads to similar crystal shapes and properties. Garnets belong to the isometric crystal class, which produces very symmetrical, cube-based crystals. The most common crystal shape for garnets however is the rhombic dodecahedron, a twelve sided crystal with diamond-shaped (rhombic) faces. This basic shape is the trademark of garnets, for no other crystal shape is so closely associated with a single mineral group like the rhombic dodecahedron is with garnets. Most garnets are red in color, leading to the erroneous belief that all garnets are red. In fact a few varieties, such as grossular, can have a wide range of colors, and uvarovite is always a bright green. As a mineral specimen, garnets usually have well shaped and complex crystals and their color and luster can make for a very beautiful addition to a collection. At times, garnets are accessory minerals to other valuable and pretty gem minerals such as topaz, beryl, tourmaline, vesuvianite and diopside making these specimens extra special.

The Garnet Group is actually a larger group than most people realize. In the table below are the more common members with their chemistries and their significant divergent properties: density (SG), index of refraction (IR), and the typical color as well as their general environment of formation. Under environment of formation: metamorphic is indicated with an M and igneous with an I. All garnets may contribute to detrital sedimentary rocks but they are not of original sedimentary origin.


Mineral Name: Chemistry: Specific Gravity: Index of Refraction: Typical Color: Environment of
Formation:
ALMANDINE Fe3Al2(SiO4)3 SG = 4.3 IR = 1.83 reddish brown to brownM-schists & gneisses; I-pegmatites (rarely)
ANDRADITE Ca3Fe2(SiO4)3 SG = 3.8 IR = 1.89 brown, black or green M-serpentinites & skarns; I-volcanic
GROSSULAR Ca3Al2(SiO4)3SG = 3.5 IR = 1.75 colorless, orange or green M-contact marbles & serpentinites
PYROPE Mg3Al2(SiO4)3SG = 3.6 IR = 1.73dark red to ruby redM-serpentinites & gneisses; I-dunites & kimberlites
SPESSARTINE Mn3Al2(SiO4)3SG = 4.2 IR = 1.80orange, pink or brown M-gneisses & marbles; I-pegmatites & granites
UVAROVITE Ca3Cr2(SiO4)3SG = 3.8 IR = 1.86greenM-serpentinites

Other rarer members of the garnet group inlcude calderite, goldmanite, henritermierite, hibschite, katoite, kimzeyite, knorringite, majorite, morimotoite and schorlomite.

The mineral yafsoanite, a tellurate, the halide mineral cryolithionite, arsenate minerals berzeliite and manganberzeliite and the vanadate mineral palenzoaite share the same structure with the Garnet Group.


Much information for this page was provided from
Fleischer's Glossary of Mineral Species


See Our Garnet Specimens
Andradite
Almandine
Grossular
Spessartine
Uvarovite

Amethyst Galleries sells natural mineral specimens, including precious metals and gemstones. For a selection of Fine Jewelry, see our affiliates:

Garnet Jewelry - Hover over an item for more information
Round Red Garnet Sterling Silver Vintage-Inspired Ring with Tanzanite - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $200.00 at Gemvara
no photoRound Red Garnet Sterling Silver Vintage-Inspired Ring with Tanzanite - Venus Band
$200.00
Gemvara
Garnet Chain Necklace in Sterling Silver, One Size
Warm in color, this garnet necklace features five round garnet gemstones set in open rings of sterling silver along a delicate chain, a simply graceful gift.Only $94.00 at Blue Nile
no photoGarnet Chain Necklace in Sterling Silver, One Size
$94.00
Blue Nile
Round Green Amethyst 14K White Gold Engagement Ring with Red Garnet & Diamond - Isabella Ring
This inspired design has a delicate wave of bezel-set gemstones curving on opposite sides of the center gemstone.Only $610.00 at Gemvara
no photoRound Green Amethyst 14K White Gold Engagement Ring with Red Garnet & Diamond - Isabella Ring
$610.00
Gemvara
Round Blue Topaz Sterling Silver Vintage-Inspired Ring with Rhodolite Garnet - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $205.00 at Gemvara
no photoRound Blue Topaz Sterling Silver Vintage-Inspired Ring with Rhodolite Garnet - Venus Band
$205.00
Gemvara
Sterling Silver Promise Ring with Rhodolite Garnet - Princess Solitaire Stackable Ring
This petite princess-cut solitaire ring, lovely and delicate alone, is designed to be perfectly stackable with other rings.Only $200.00 at Gemvara
no photoSterling Silver Promise Ring with Rhodolite Garnet - Princess Solitaire Stackable Ring
$200.00
Gemvara
Round Sapphire Sterling Silver Mother's Ring with Red Garnet - Liana Ring with Three Gems
This lovely leafy vine ring twines across the finger while brilliant gems bloom among the leaves.Only $195.00 at Gemvara
no photoRound Sapphire Sterling Silver Mother's Ring with Red Garnet - Liana Ring with Three Gems
$195.00
Gemvara
7.25 ct. t.w. Garnet Tennis Bracelet in Sterling Silver. 7.5"
Brilliant 7.25 ct. t.w. garnet gemstones twinkle like colored lights around the wrist. Sterling silver bracelet. Garnet birthstones are the perfect gift for January birthdays.Only $89.95 at Ross-Simons
no photo7.25 ct. t.w. Garnet Tennis Bracelet in Sterling Silver. 7.5"
$89.95
Ross-Simons
Round Black Onyx Sterling Silver Vintage-Inspired Ring with Red Garnet & Amethyst - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $200.00 at Gemvara
no photoRound Black Onyx Sterling Silver Vintage-Inspired Ring with Red Garnet & Amethyst - Venus Band
$200.00
Gemvara
Garnet and White Topaz Halo Bracelet in Sterling Silver, One Size
A great complement to any style, this gemstone bracelet showcases garnet accented with a sparkling halo of pave-set white topaz framed in sterling silver.Only $595.00 at Blue Nile
no photoGarnet and White Topaz Halo Bracelet in Sterling Silver, One Size
$595.00
Blue Nile
Round Amethyst Sterling Silver Promise Ring with Aquamarine & Red Garnet - Modern Heart Ring
This stylishly-simple heart ring is carefully handcrafted in your choice of gems and metals.Only $200.00 at Gemvara
no photoRound Amethyst Sterling Silver Promise Ring with Aquamarine & Red Garnet - Modern Heart Ring
$200.00
Gemvara
Round Red Garnet Sterling Silver Promise Ring - Petite Claddagh Ring
A petite version of the traditional Irish Claddagh Ring. This ring is given as a token of love or marriage and is carefully handcrafted in your choice of gems and metals.Only $130.00 at Gemvara
no photoRound Red Garnet Sterling Silver Promise Ring - Petite Claddagh Ring
$130.00
Gemvara
Round Rhodolite Garnet Sterling Silver Vintage-Inspired Ring with Red Garnet & Aquamarine - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $205.00 at Gemvara
no photoRound Rhodolite Garnet Sterling Silver Vintage-Inspired Ring with Red Garnet & Aquamarine - Venus Band
$205.00
Gemvara
Round Citrine Sterling Silver Vintage-Inspired Ring with Red Garnet - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $200.00 at Gemvara
no photoRound Citrine Sterling Silver Vintage-Inspired Ring with Red Garnet - Venus Band
$200.00
Gemvara
Round Rhodolite Garnet Sterling Silver Vintage-Inspired Ring with Red Garnet & Amethyst - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $200.00 at Gemvara
no photoRound Rhodolite Garnet Sterling Silver Vintage-Inspired Ring with Red Garnet & Amethyst - Venus Band
$200.00
Gemvara
Round Fire Opal Sterling Silver Vintage-Inspired Ring with Citrine & Red Garnet - Venus Band
Scalloped shells form a fluted pattern on each side of this feminine tapered band, carefully handcrafted in your choice of gems and metals.Only $205.00 at Gemvara
no photoRound Fire Opal Sterling Silver Vintage-Inspired Ring with Citrine & Red Garnet - Venus Band
$205.00
Gemvara

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