Garnet Classification: (Ref. 12 and 15)
Garnets are a group of isometric nesosilicates with the general chemical formula X2Y3 (SiO4)3. The”X” and “Y” represent sites in the crystal structure that are occupied by a variety of ions. The X-site may contain Ca2+, Mg2+, Fe2+ or Mn2+; while Al3+, Fe3+, Cr3+, Ti4+, Mn3+, V3+, or Zr3+ can occupy the Y-site, also referred to as the octahedral site. In addition, Al3+, Fe3+, or Ti4+ occasionally replaces silicon in the tetrahedral (SiO4)3 site of some of the more rare garnet species. Nesosilicate minerals are those minerals where the silicate tetrahedrons (SiO4) are unbonded to other tetrahedrons. The common Garnets are 1. Almandine, 2. Pyrope, 3.Andradite, 4.Grossularite,
5. Spessartine, and 6. Uvarovite. There are also 9 rare Garnet spices which are seldom seen.
Garnet Names: : http://www.mineralminers.com/html/garminfo.htm#backinfo
The name garnet is from the Latin word granatus which originated when garnet grains in rock were compared to the dark red seeds of the pomegranate fruit.
Pyralspite is derived from the names of the three garnet species in its group: Pyrope, almandine, and spessartine, with 'ite' added to the end.
Ugrandite is derived from the names of the three garnet species in its group: Uvarovite, grossular, and andradite, with 'ite' added to the end.
Almandine was named after the ancient locality Alabander in Asia-minor, where once many garnets were cut and polished.
Pyrope is from the Greek for fire-like, referring to its color.
Spessartine was named for a locality in the Spessart district in Bavaria.
Andradite was named after the Portuguese mineralogist d'Andrade.
Grossular was named after the gooseberry R. grossularia, because of the similar pale green color of the original specimens.
Uvarovite is named after the Russian mineralogist Count Sergei Simonovitch Uvarov.
Rhodolite is from the Greek rhodon meaning rose, referring to its color.
Malaia is from the Swahili word malia meaning out of the family, referring to the fact that this garnet variety typically has some distinctively different physical properties than other garnets found in the same area.
Tsavorite is named after the Tsavor Game Preserve of Kenya, near which it was discovered.
Demantoid is from the French demant meaning diamond, in allusion to its similar brilliance.
Melanite is from the Greek melanos meaning black, referring to its color.
Topazolite named after its similarity to yellow topaz.
History of Garnet: (Ref. 15)
Garnet and Ancient History
Garnet jewelry has been found that date back to the Bronze Age (~3000 BC). The majority of this ancient jewelry was a very primitive style of lapidary found among the graves of a village of lake dwellers. Other documentation of ancient jewelry containing garnet have been found among remains located in Sweden between 1100 and 2000 B.C., in Samaria around 2300 B.C. and in Egypt in 3100 B.C.
Garnet and Greek History
As early as the later years of 400 B.C., garnet jewelry was found in Greece. More specifically, signet rings found (in this area of Europe) were discovered. It is believed that Greeks were the first to use garnet at this capacity. Garnet has also been documented as a largely admired treasure in Greece during the 3rd and 4th centuries. The other history that Greece holds with garnet is its role in providing the root nomenclature for the garnet family of stones.
Garnet and Egyptian History
As mentioned above, garnet had been found as early as 3100 B.C. in Egypt. It has further been noted that early Egypt popularly adorned garnet in amulets and talismans. Garnet was also believed to be buried within the tombs of the dead for protection and light through the passage of after death experience.
Garnet in Biblical History
It is believed that in n the Old Testament when Noah set forth in the Ark he utilized garnet to light his path and to illuminate the Ark. The garnet is also one of the twelve stones that represent today's birthstone, that adorn the breastplate of the high priest Aaron (Exodus 39). The original breastplate of the High Priest was said to be made by Moses in mid 1200 (B.C.) according to divinely inspired instructions he received during forty days in the wilderness. Around the middle and late 1300 (B.C.) twelve stones had been chosen to be representative of the twelve tribes of Israel. (Exodus 28: 17-21) Among these stones garnet was chosen as the gem representing the tribe of Judah one of the sons of Jacob. These two biblical references became part of the first association of a particular semi-precious gem with a particular month. Garnet is also believed to have been worn by King Solomon in times of battle.
Garnet, in the Middle Ages and Medieval History
Garnet is believed to have served many medicinal purposes some of which were recorded throughout Medieval History. Documents dating from this time period state that garnets had been believed to protect one from poisons. Other sicknesses were believed to be cured by garnet including those dealing with blood and infection. Many curing huts of the Middle-Ages were believed to carry garnets. Often mistaken for rubies, garnet was found among corpses found to date back to the Middle-Ages.
Garnet Locations:
Pyrope: China, Madagascar, Myanmar, South Africa, Sri Lanka, Tanzania, USA
Rhodolite: Brazil, India, Sri Lanka, Thailand, USA
Almandite: Brazil, India, Madagascar, Sri Lanka and the United States. Smaller deposits exist in Austria and the Czech Republic. Almandine garnet star-stones are found in India and the United States (Idaho).
Spessartite: Brazil, China, Kenya, Madagascar, Myanmar, Namibia, Sri Lanka, Tanzania, USA. The best specimens come from Namibia and are called "Mandarin Spessartine (Spessartite) "
Grossularite: Canada, Kenya, Mali, Pakistan, Russia, South Africa, Sri Lanka, Tanzania, USA
Hydrogrossular: Myanmar, South Africa, Zambia
Hessonite: Brazil, Canada, Madagascar, Sri Lanka, Tanzania, USA
Leuco garnet: Canada, Mexico, Tanzania
Tsavorite: Kenya, Tanzania
Andradite: Russia
Demantoid: China, Korea, Russia, USA, Zaire
Melanite: France, Germany, Italy, USA
Tapazolite: Italy, Switzerland, USA
Uvarovite: Canada, Finland, India, Poland, Russia, USA
Interesting Garnets Stories:
Garnet Crystal - New York City: (Ref. 9, Page 346) “The finest large garnet crystal ever found in the United States was discovered, strange though it may seem, in the midst of the solidly build portion of New York City, by a laborer excavating for a sewer in West Thirty-fifth Street, between Broadway and Seventh Avenues, in August, 1885. The laborer took it to Mr. J. J. King, who lived in the vicinity from whom the author received it, and it is now deposited as a loan in the cabinet of the New York Mineralogical Club, at the American Museum of Natural History, Central Park, new York. In form, the crystal is a combination of the tetragonal trisoctahedron (trapezohedron), the predominating form with the dodecahedron and the hexoctahedron. It weighs 9 pounds and 10 ounces (4.4 kilos.), and measures 15 centimeters (6 inches) in its greatest diameter, and 6 centimeters on its largest trapezohedron face. Twenty of the trapezohedron faces are perfect, while the remaining four were obliterated in the formation of the crystal by pressure against the quartzite matrix. On the surface the color is a reddish-brown, with an occasional small patch of what is apparently chlorite, which enhances its beauty as a specimen. On a fractured surface, however, the color is a light almandine, and the material in the interior of the crystal is found to be very compact.”
Record Price for Garnet Jewelry: At the auction of the Estate of Jacqueline Kennedy-Onassis at Sotheby's on April 24, 1996, a striking cabochon garnet flower brooch from the 19th century was sold for $145,000.
Record Size Gem Garnets: “Mr. G. F. Kunz reports, on the authority of Mr. W. E. Hidden, that several crystals of rhodolite were found, during the summer of 1901, embedded in a decomposed saprolititic rock; these crystals are of considerable size, one weighing 3&1/2 pounds and yielding 300 carats of the red material, free from flaws and suitable for cutting.” (Ref. Precious Stones, Max Bauer, 1982)
Record Crystal Size - Norway: The largest documented (and proven) garnet crystal on record was a 2.3 meter garnet. It measured 10 cubic meters in volume and the weight was estimated to be 37,500 kilograms. This and other large crystals are summarized in an article entitled The Largest Crystals by Peter C. Rickwood in American Mineralogist, Volume 66, pages 885-907, 1981.
Record Size Pegmatite Crystal Pocket: In 2004, fantastic sculptured red spessartine etched garnets from Brazil showed up at the Tucson Show. A paragraph on this find, from the web from the Mineral logical Society of America reads as follows:
“This is to inform you and the Pegmatite Interest Group about an outstanding pegmatite find in Brazil
in a sub-horizontal pegmatite called Navegador mine, in Conselehiro Pena, Minas Gerais, a huge cavity measuring (after dug ) about 10 x 10 x 3 meters, several tons of large ( up to 2 to 3 tons) high-grade quartz crystals were found, together with several tens of tons of albite (everything collapsed inside the pocket), but the most interesting is that inside the albite there were more than 100 kg of etched spessartite crystals, very bright and nice red, measuring up to 10 cm, and over the cleavelandite plates, and also over the quartz crystals, there were helvite crystals measuring 5 to 8 mm, yellow to olive-green; inside most of the helvites there is manganese oxyde.”
Color Change Garnet: Color Change Garnet is one of the rarest, interesting and phenomenal of all gemstones. An extremely rare variety of Malaia Garnet, Color Change Garnet is in fact a mixture of Pyrope and Spessartite Garnet. The color change can be intense and equal to the color change of top quality Alexandrite. As a result, Color Change Garnets can easily be mistaken for Alexandrite. Some of the best Color Change Garnets are mined from a deposit in Bekily, Southern Madagascar. Color Change Garnets from this mine are well known for their strong Alexandrite like color change. Other well known sources of Color Change Garnet are Songea and Tunduru in Tanzania.
Rainbow Garnet: Rainbow garnet is a variety of andradite that sparkles with opal like rainbow colors by iridescence. Its output is very sporadic, and only a few localities were reported in the world so far. The first discovery was made in Adelaide mine, Nevada, USA, in 1934 and research on the cause of its play of color was carried on, but the material was not in gem quality and did not make a debut in the market. Sonora in Mexico became famous for producing the material for gem market, but its output had been very low from the beginning and the products disappeared soon after circulation in the market for several years in the late 1980s. Recently (2004) small amount of rainbow garnet was found in Tenkawa village, Yoshino district, Nara pref. Japan. The material bears comparison with, or even superior to, that from Mexico which was once circulated in the market.
(to be continued next month)
