GARNET
The garnet family is interesting for a multitude of reasons. They have been used by humans since the bronze age & Ancient Egyptians. Mostly as abrasives and when found in high quality even in jewellery. Even now we are still finding new varieties of garnet never before seen, such as the rare colour changing blue/red garnets from Bekily, Madagascar.
AN INTRODUCTION TO GARNETS
Garnets are generally found in Metamorphic rocks. These rocks are substantially altered igneous (Fire born) rocks that turned from a fluid magma state by slowly cooling down and crystallizing. These igneous rocks were then subjected to varying states of pressure, temperature & mineral rich fluids. In certain areas around the world these conditions where just right for garnets to start to form in the now Metamorphic rocks. Garnets can be found almost anywhere due to the fact that Metamorphic rocks are very common and make up about 12% of the Earth’s crust.
The oldest confirmed garnets used by man date back to 3100 B.C. in Egypt where these gemstones had a multitude of uses. The lesser quality garnets were usually ground to a course dust that was used as an abrasive to precisely cut large limestone and granite blocks which were used for construction. The higher quality gems were too valuable for industrial use and usually ended up in statement pieces of jewellery.
Although garnets in general aren’t particularly rare, certain varieties so rare that they have only recently been discovered. Amongst the well-known garnet varieties it is generally accepted that Demantoid garnets are the rarest, these stunning brown to intense green gems are found in a few places on earth but all exhibit a brilliant multicoloured fire that gemmologists refer to as “dispersion”. This dispersion closely resembles that of Diamond, the name Demantoid means “Diamond-like”.
Garnets are found in practically every color known, apart from pure blues. Some of the more well-known varieties are:
- Spessartite Garnet:
Brownish orange to vivid orange in color, these spectacular gemstones are sometimes referred to as “Mandarin garnet” when they exhibit the highly sought after vivid orange hue.
- Grossular Garnet:
These often green gemstones actually are found in a plethora of color ranging from raspberry reddish pink to neon green. These green hues when saturated enough are called Tsavorite garnets and are amongst the rarest and most valuable green gemstones known.
- Pyrope Garnet:
Pyrope garnets are considered a more common garnet variety and have a dark deep red color. They’re found on every continent.
- Andradite garnet:
These diamond-like garnets can also be called Demantoid garnets. They were originally only found in Russia and were so rare that they were only really meant for the Tsars. Some of these fine gemstones contained asbestos needle inclusions resembling a horse’s tail and are therefore called “horsetail inclusions”. Nowadays the most well-known localities for this rare gemstone are Russia, Madagascar and Namibia.
- Almandine garnet:
Almandine garnets are actually pretty similar to Pyrope garnets but contain a lot more Iron as opposed to the Magnesium rich Pyrope garnets. They are also similar in color and tend to be found in deep red hues.
INTERESTING FACTS
Garnets have the interesting ability to actually mix with different varieties of eachother to create new “hybrid garnets”. E.g. Pyrope-Almandine garnets are usually referred to as Rhodolite garnets and tend to be a rich Magenta in color.
Garnets belong to the cubic crystal system and tend to form into beautiful Rhombic Dodecahedral crystals.
Some garnets can display a color change effect, this is generally caused by two or more different garnet varieties being present in the crystal structure.
