The garnets
Garnets are quite popular silicate minerals on Earth. Their general chemical formula is X3Y2(SiO4)3 where the position of X and Y is occupied by different metals. For example:
In the place of X may be calcium, magnesium, iron or manganese (Ca, Mg, Fe, Mn)
In the place of Y may be aluminum, iron, chromium, titanium, zirconium or vanadium (Al, Fe, Cr, Ti, Zr, V)
The most popular garnets 
are:
Almandine -Â Fe3Al2[SiO4]3 - red, brown
Andradite -Â Ca3Fe2[SiO4]3 - green, yellow, black
Grossular - Ca3Al2[SiO4]3 - green, yellow, red, pink, clear
Pyrope -Â Mg3Al2[SiO4]3 - red, purple
Spessartine -Â Mn3Al2[SiO4]3 - orange, red, brown
Uwarovite -Â Ca3Cr2[SiO4]3 - green
All the garnets crystallize in the regular system, and they are most often found in the rhombic dodecahedral crystal habit or deltoidal icosikaitetrahedron crystal habit. Those names sound very scary so below are shown their geometrical models:
When thinking of garnet gemstones, most people think of red garnet. Garnet most commonly occurs in red, and the origin of the name "garnet" lies in this deep red hue. The name "garnet" comes from the Medieval Latin word, "granatum", which is an adjective meaning "dark-red". It is thought that this adjective could have been extracted from the word "pomegranate", due to the color of the seed coats or shape of the seeds. However, the word could also have come from another Medieval Latin word; "granum", referring to red dye. The use of red garnet dates back thousands of years, when it was used by Egyptian pharaohs for both decorative and ceremonial purposes. The ancient Romans also wore garnet rings and traded garnet gemstones.
The color of garnets is in fact highly dependent on their chemical composition. It is also the main factor of garnets quality and rarity. Although red is the most commonly occurring color, garnet occurs in almost every color. They are found as red, orange, yellow, green, purple, brown, blue, black, pink and colorless. Blue is very rare. Sometimes garnet’s color changes and it depends on the angle of light inside. Jewellery use garnets when they are transparent (transmit light) and have no dirt or inclusions of other minerals inside.Â
Other features of garnets: As minerals garnets are brittle, that mean they crush up to smaller fragments when stroked by a hammer. There are also relatively hard, and that mean, it is difficult to scratch a garnet with a sharp, metal instrument.
Frequently one can observe them in metamorphic rocks - mica gneisses and schists, rarely in igneous rocks. The sedimentary rocks like to create concentrations of garnets, such as sandback on the beaches (heavy minerals like a garnets are sorted and separated from lighter quartz sand). The largest known garnet specimen was found in Norway and has 2.5 m in diameter and weights 37 tons.
Large deposits of red garnet were discovered in Bohemia (Central Europe) around the 16th century, which became the focus of the jewelry industry in the area. Bohemian garnet from Czechia continues to be mined today. Although red is the most commonly occurring color, garnet occurs in almost every color.
Garnet is found all over the world. Different types of garnet occur in different locations. One of the most recently discovered colors of garnet is rare blue garnet, which was discovered in the late 1990s in Madagascar. It has since been found in other regions, including the USA, Russia, Kenya, Tanzania and Turkey.
The following shows the type of garnet and place where it is usually found:
Pyrope: Brazil, China, Madagascar, Myanmar (Burma), South Africa, Sri Lanka, Tanzania and the USA.
Rhodolite: Brazil, India, Sri Lanka, Thailand and the USA.
Almandine: Brazil, India, Madagascar, Sri Lanka and the USA. Smaller deposits exist in Austria and the Czech Republic.
Star Garnet: Star-stones are found in Madagascar, India and the United States.
Spessartite: Brazil, China, Kenya, Madagascar, Myanmar (Burma), Namibia, Sri Lanka, Tanzania and the USA. Some of the best specimens come from Namibia and are referred to as "Mandarin garnet".
Color Change Garnet: East Africa, Sri Lanka (Ceylon), Magagascar, United States, Norway, Tanzania and Tunduru.
Mali Garnet: Mali, West Africa
Malaya Garnet (Malaia): Tanzania and Kenya, East Africa
Hydrogrossular: Myanmar (Burma), South Africa and Zambia.
Hessonite: Brazil, Canada, Madagascar, India, Tanzania and the USA.
Leuco garnet: Canada, Mexico and Tanzania.
Tsavorite: Kenya and Tanzania.
Demantoid: Russia, China, Korea, USA and Zaire.
Melanite: France, Germany, Italy and the USA.
Topazolite: Italy, Switzerland and the USA.
Uvarovite: Canada, Finland, India, Poland, Russia and the USA.
Garnets occurs in may colours but also has many uses: they are used in practice as water cutting, abrasive blasting media, water filtration granules and abrasive powders. Because of the beautiful color garnets are also valued material for jewellery (especially when clean with no inclusions) and for mineral collections.
Questions:
- Close to the main coordinates
find quite a big aggregation of garnets (shown in the photo). What is the size of this aggregation and in what place is it located?
- What type of garnets (out of the listed above) are the ones in the aggregation? What metals are present in this type?
- Look around, do you see more garnets? Where?
- Walk to the "Bench" waypoint and take a rest.
You should see two busts in front of you. Now take a look at the bench. What percentage of its surface is covered by garnet aggregations? What is the size of the biggest crystals that you can see within them?
- Look below the bench. Is there any difference between the horizontal part of this seat and the two blocks supporting it?
Do not write your answers in the online log! Send them to me through e-mail or Message Center. Then you may log this EarthCache as found. I will contact you if corrections or clarifications are needed.
No spoiler photos in logs, please, but you are encouraged to photograph yourself with the two bronze gentelmen and to add the photo to your log. And, please, please, no fake finds! I really hate to delete logs but I do it if I need...
We were able to identify these garnets here thanks to the lesson brought by another Earthcache placed in another part of the world - in Kraków, in Poland. This is the cache: GC60EM9. Its Author - Zielony Team - gave us their permission to use a part of the materials. Thanks!
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