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The Insight
Red Garnets were originally not used as jewelry as some Asiatic tribes and some North American Indians used them as bullets believing that the gems could 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 Islamic’s, garnets illuminate the fourth heaven. In more modern times, garnet is the birthstone for January.
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. Almandite, pyrope, and spessartite belong to one series. Grossularite and andradite (includes the tsavorite and demantoid 'varities') 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 various sizes 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 one of 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, monocloni, 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.
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. This is the reason for the many varieties for garnet.
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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. Its name comes from an ancient gem cutting center in Turkey. |
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Rhodolite |
A distinctive purplish color resembling a rose (from whcih it takes its name -- Greek for 'rhodon'). |
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Pyrope |
Purplish red, pinkish red, orangy red, crimson, and dark red. It has also recently been found in pink. The name comes form the Greek 'pyropos' meaning 'fiery-eyed'. Its red color comes from the presence of iron plus chomium. |
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Spessartite |
Red, reddish orange, orange, yellow brown, reddish brown and blackish brown. They are named for the Spessart district of Bavaria. |
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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. |
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Tsavorite |
An intense green grosularite. Its name comes from the Tsavo park in Kenya where it was originally discovered. It is colored by vanadium and chromium--the same elements that color emeralds. |
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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. |
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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 |
The Sources
Garnets come from many different countries in the world, including all six continents and several states in the U.S. Some special sources have already been cited. Other special location are:
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Pyrope |
Near Trebnitz, Chechoslovakia, the so-called 'Bohemian' garnets. |
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Almandite |
Ceylon (fine color and large size), Idaho (stars), and Madagascar (large sizes). |
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Spessartite |
San Diego County (good crystals -- fine orange), Virginia (fine deep orange to deep brown), Brazil (large crystals--fine color | |
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