Facets Garnets 1

The Lore: Red Garnets are sidewinder missiles? A far cry from use as jewelry, but some Asiatic tribes and some North American Indians used them as bullets believing the would seek blood and inflict deadlier wounds. But on the flip side of the coin, ancient apothecaries ground garnets into powder and used them as a poultice -- red for fever; yellow for jaundice. They were also thought to stop bleeding, cure inflammatory diseases, and settle the nerves. But for some, if the garnet lost its luster, that was a signal of impending doom. For Christians, the red garnet symbolizes Christ's blood. For Islamics, garnets illuminate the fourth heaven. Garnets trace its roots as a gemstone to the Nile Delta in 3100 B.C., where Egyptian artisans would craft garnets into beads or inlay garnet into hand-wrought jewelry. In more modern times, garnet is the birthstone for January. Garnet may be given as a gem on the 2nd and 6th wedding anniversary.

The Details: The name "garnet" derives from the Latin for "grain" because of its rounded crystals. And the term refers to a "group" of a half-dozen different "species" that all have essentially the same crystal structure. But their chemical composition may differ, resulting in different "series" within the group. There are six species of common garnets based on ideal end-member chemical compositions. These six species are divided into two groups; the pyralspite group which are the pure chemical end-members Fe3Al2(SiO4)3 (almandine), Mg3Al2(SiO4)3 (pyrope) and Mn3Al2(SiO4)3 (Spessartine), and the ugrandite group or calcium garnet group consisting of Ca3Fe2(SiO4)3 (andradite), Ca3Al2(SiO4)3 (grossular), and Ca3Cr2(SiO4)3 (uvarovite). Garnet is allochromatic, meaning that most of the color variations in different garnets are due to their highly variable trace element impurities rather than to their bulk composition elements. The color we see in garnets is produced when light is selectively absorbed by these ions or by interactions between these ions (intervalent charge transfers)

The Varieties:

Almandite: Deep red, brownish red, brownish black, and violet red. It is the most common red garnet. There is also a star variety showing four to six rays (Idaho Star Garnet being the most common.). Its name comes from an ancient gem cutting center in Turkey. Almandine is one of the aluminum garnets, along with pyrope and Spessartine (the "pyralspite" group). Its composition is Fe3Al2(SiO4)3, with the silica groups (SiO4) being isolated, not linked in chains or sheets as in most silicate minerals. Pyrope and Spessartine have magnesium and manganese, respectively, instead of the iron (Fe).

Rhodolite: A distinctive purplish color resembling a rose (from which it takes its name -- Greek for "rhodon").

Pyrope: Purplish red, pinkish red, orangy red, crimson, and dark red. It has also recently been found in pink. Its name comes form the Greek "pyropos" meaning "fiery-eyed". Its red color comes from the presence of iron plus chromium.

Spessartite: Red, reddish orange, orange, yellow brown, reddish brown, and blackish brown. They are named for the Spessart district of Bavaria.

Grossularite: Colorless, white, gray, yellow, yellowish green, green of various shades, brown, pink, reddish, and black. As mentioned previously, it was named for the gooseberry. The translucent green color is sometimes sold as "African jade", or as "Transvaal jade", because it looks like jade.

Tsavorite: Tsavorite is an intense green variety of grossular garnet named after the Tsavo park in Kenya where it was originally discovered in 1967. It is one of the newest of the precious gemstones. It is colored by vanadium and chromium--the same elements that color emeralds. But it is more durable than emeralds, it is also more highly dispersive and refractive.

Andradite: Yellow green, green, greenish brown, brown, grayish black, and black. If they contain either titanium or manganese, the color may resemble grossular. As mentioned previously, its name comes from a Portuguese mineralogist of the late 18th and early 19th centuries.

Demantoid: The most important variety of andradite, that varies from light to dark yellowish green. Its name comes from the old German "demant" (diamond). It has the highest "dispersion" of any natural colored stone normally seen in the jewelry industry.

Grossularite and andradite (includes the tsavorite and demantoid "varieties") belong to another series. There also are mixtures. For example, rhodolite is a combination of almandite and pyrope. Another common mix is almandite/spessartite and another is pyrope/spessartite.

Almandite, rhodolite, and spessartite are the most popular because of their desirable colors. Pyrope is rarely seen in modern jewelry, is rare in sizes over two carats, and is most often seen in antique pieces. It was the "fashion stone" of the 18th and 19th centuries. Grossularite is named for "grossularia" -- the botanical name for gooseberry -- because of its resemblance to the gooseberry. Andradite is named for a Portuguese mineralogist named Andrada.

A typical garnet crystal is about one-half to an inch in diameter. Fashioned stones are commonly available in sizes from melee to ten carats or more. And a few spessarites in Brazil have weighed several pounds. But these are rare. The Smithsonian has an Almandite weighing 40.60 carats, a Rhodolite weighing 74.30 carats, and a spessartite weighing 109.00 carats, and other large specimens. A museum in Vienna has the best collections of pyrope.

The Structure Garnet is a silicate mineral that has a vitreous (glassy) luster. All minerals are classified into six different crystal systems based on the shapes of their smallest unit cells. They are isometric (also called cubic), tretragonal, orthorhombic, monoclonic, triclinic, and hexagonal. Garnets are the first of these, i.e., isometric. Such crystals are cube shaped and tend to have equal dimensions. They have three crystallographic axes of equal length, each perpendicular to the other two. They have no cleavage but display a conchoidal fracture, so are somewhat brittle and tend to chip easily. Yet garnet jewelry will give many years of wearing pleasure if cared for properly.

The Myths: Legend has it, that Noah suspended a finely cut, glowing garnet to illuminate the ark. In medieval times garnets were thought to cure depression, protect against bad dreams and relieve diseases of the liver and hemorrhages. The Amazon women were said to been empowered by the garnets they wore on their breastplates. They were popular for jewelry in the 18th and 19th centuries. It was a mark of distinction to use slices of garnet in the windows of churches and temples.

Garnets is the stone of new beginnings, especially because it is the birthstone of January. Garnet is given and received as a symbol of consistency, perseverance, and good health. It is a power stone, and, according to legend, it guides its wearer when he’s traveling at night. This is a stone of commitment and fidelity, especially for women (this is one of the reasons it was so popular in jewelry). Wearing the red garnets, because they are the color of blood, promotes good circulation, especially in the lower half of the body. Thus, they are also good for fertility. They help promote passion between lovers. Wearing the green garnets promotes great vitality and growth as well as attracting abundance.

The Locale: Most garnets are found in pegmatites--the most prolific of the gem deposits. Pegmatites were formed when molten rock, rich in water and other fluids, was squeezed into fissures in surrounding non-molten rock. When the mixture began to cool, crystals began to form (to grow) at the outer walls first, then toward the center. Different available elements and different temperature and pressure created zones of different gem crystals. Although only a small percentage of pegmatites contain worthwhile gem crystals, they produce more gems in more varieties than any other type of deposit. Thus the reason for the many varieties of garnet.

The Unusual: A small number of Garnets are pushed up from the pegmatite by ants. This is especially true in Arkansas and Arizona. The Garnet is very high in Chromium and has a fiery red color when exposed to strong light. They generally are under 1 carat in weight and are known as ant hill Garnets.

During the 1800's Navajos in this locale used the water-worn and rounded ant Hill garnet crystals as bullets. This use had both a practical side (the stones were there, and free) and an emotional appeal… the Navajos believed the blood-red color helped produce fatal wounds. Ant hill garnets occur in a remote section of the Navajo Nation in Arizona. The gems have never been mined commercially because there aren't enough of them.

Properties: Crystal System - Isometric (Cubic) Habit - Usually euhedral. Dodecahedra common.

Hardness - 6.5-7.5 (reds 7-7.5; others softer) Cleavage - None Fracture - Conchoidal

Specific Gravity Refractive Index varies by variety

Spessartine 4.15 (4.12-4.20) 1.81 (1.79-1.814) Almandine 4.05 (3.93-4.30)1.79 (1.76-1.82) Andradite3.84 (3.77-3.88)1.89 (1.88-1.89) Demantoid 3.84 (3.81-3.87)1.888 (1.85-1.89) Rhodolite3.84 (3.74-3.94)1.76 (1.75-1.77) "Malaia" 3.81 (3.78-3.85)1.76 (1.742-1.78) "Pyrope" 3.78 (3.62-3.87)1.74 (1.71-1.77) Grossular 3.61 (3.57-3.73)1.74 (1.73-1.76) Hessonite 3.65 1.74-1.75 Tsavorite 3.64 1.742-1.744

Color: All shades of red and pink; also yellow, green, black, brown, orange (no blue).

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