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
.10ct t.w. Rhodolite Garnet Butterfly Pendant Necklace. 18"
Our butterfly pendant necklace has free-form open wings aflutter with .10 ct. t.w. rhodolite garnets. Suspends from a cable chain with a springring clasp. Sterling silver pendant necklace.Only $75.00 at Ross-Simons
no photo.10ct t.w. Rhodolite Garnet Butterfly Pendant Necklace. 18"
$75.00
Ross-Simons
Round Black Onyx Sterling Silver Ring with Rhodolite 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 Ring with Rhodolite Garnet & Amethyst - Venus Band
$200.00
Gemvara
Garnet Bezel-Set Drop Necklace in Sterling Silver, One Size
Featuring two deep red, bezel-set garnets, this modern necklace, featuring a one and a half-inch drop, is crafted from timeless sterling silver.Only $69.00 at Blue Nile
no photoGarnet Bezel-Set Drop Necklace in Sterling Silver, One Size
$69.00
Blue Nile
Sterling Silver Bracelet with Rhodolite Garnet - Gemstones By The Yard Star Of David Bracelet
A layerable essential, handcrafted in your choice of gems and metals, featuring a Star of David in pave-set gemstones. Adjustable 7-7.5 chain."Only $270.00 at Gemvara
no photoSterling Silver Bracelet with Rhodolite Garnet - Gemstones By The Yard Star Of David Bracelet
$270.00
Gemvara
Garnet Milgrain Necklace in Sterling Silver (5mm), One Size
Show off a classic with this granet gemstone necklace, framed in sterling silver and finished off with vintage milgrain detailing. This necklace can be worn at 16 and 18 inches.Only $99.00 at Blue Nile
no photoGarnet Milgrain Necklace in Sterling Silver (5mm), One Size
$99.00
Blue Nile
Round Rhodolite Garnet Sterling Silver Ring with Rock Crystal - 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 $195.00 at Gemvara
no photoRound Rhodolite Garnet Sterling Silver Ring with Rock Crystal - Venus Band
$195.00
Gemvara
Round Red Garnet Sterling Silver Ring with Amethyst & London Blue Topaz - 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 Red Garnet Sterling Silver Ring with Amethyst & London Blue Topaz - Venus Band
$205.00
Gemvara
Heart Garnet Ring in Sterling Silver (8mm), One Size
Love sparkles with this heart shape gemstone ring featuring a faceted garnet set in sterling silver.Only $99.00 at Blue Nile
no photoHeart Garnet Ring in Sterling Silver (8mm), One Size
$99.00
Blue Nile
Sterling Silver Ring with Red Garnet & Pink Tourmaline - Remember Forever Ring
Two gems wrapped in a knot to remember this moment forever.Only $155.00 at Gemvara
no photoSterling Silver Ring with Red Garnet & Pink Tourmaline - Remember Forever Ring
$155.00
Gemvara
Round Red Garnet Sterling Silver Ring - Timeless Knot Ring
An elegant ring with a 5mm center stone, this knot is carefully handcrafted in your choice of gems and metals.Only $190.00 at Gemvara
no photoRound Red Garnet Sterling Silver Ring - Timeless Knot Ring
$190.00
Gemvara
Round Ruby Sterling Silver Ring with Rock Crystal & 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 Ruby Sterling Silver Ring with Rock Crystal & Red Garnet - Venus Band
$205.00
Gemvara
Sterling Silver Ring with Rhodolite Garnet - Daisy Ring
This nature-inspired ring is the perfect everyday choice with a pretty petite gem-set bloom on a delicate modern band. Wear more than one to create a bouquet for your finger.Only $175.00 at Gemvara
no photoSterling Silver Ring with Rhodolite Garnet - Daisy Ring
$175.00
Gemvara
Round Tanzanite Sterling Silver Ring with Tanzanite & 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 Tanzanite Sterling Silver Ring with Tanzanite & Red Garnet - Venus Band
$200.00
Gemvara
6.50ct t.w. Garnet Drop Earrings, Diamond Accents in 14kt Yellow Gold
Our divine drop earrings showcase pear-shaped garnets of 6.50 ct. t.w. in roped settings crested with diamond accents. Wear for a sultry look. Leverback, textured and polished 14kt yellow gold earrings. Garnet birthstones are the perfect gift for...Only $185.50 at Ross-Simons
no photo6.50ct t.w. Garnet Drop Earrings, Diamond Accents in 14kt Yellow Gold
$185.50
Ross-Simons
Round Black Onyx Sterling Silver Ring with Rhodolite Garnet & Rock Crystal - 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 $195.00 at Gemvara
no photoRound Black Onyx Sterling Silver Ring with Rhodolite Garnet & Rock Crystal - Venus Band
$195.00
Gemvara

Popular Members of the Silicates Class








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