Posted: August 4, 2008 at 11:42 am
Peridot is usually pronounced as pair-uh-doe and it’s an array of olivine (not a certified mineral) that is consisted of two minerals known as fayalite and forsterite. Fayalite (Fe2Si04) is iron rich while forsterite (Mg2Sio4) is a manganese rich mineral. To show the exchange of magnesium and iron; olivine is chemically formulated as (Mg, Fe) 2Sio4. Though iron serves as a coloring agent for Peridot, yet in composition Peridot is often nearer to forsterite instead of fayalite. A peridot, which has less than 15% of iron and has some trace elements like nickel and chromium, is considered the best in color.
A large number of gemstones that have a mineral origin form in the crust of the earth. But peridot and diamond are two such elements as form deeper in the earth and this deeper region is known as mantle. Peridot crystals are found 20 to 55 miles deeper and they pop up on the surface due to tectonic or volcanic activity. Similarly, diamonds form around 100-150 miles below the surface where temperatures and pressures are extreme.
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Posted: July 24, 2008 at 1:26 am
A wide range of gemstones is consisted of minerals with a crystal like structure but we must keep in mind that all gems are not gemstones as they have an organic origin. They take their shape because of biological processes that can be animals or plants as well.
These organic gems are not found in a wide range but they include some usual varieties that are considered very important in the gem business. Amber, coral, jet, ivory and pearl are some member of this organic gem family.
Amber is considered as the fossilized toughen organic substance of the pine tree that came into being almost 50 million years back. The use of amber in jewelry, religious objects and amulets is as old as hills; it has been used in these things since prehistoric times. There is addition of insects, plants or pyrites in the pieces of amber which are considered the most prized. Kaliningrad in Russia is the place where the largest deposits of amber are found in the world. There are also large reserves of the amber in the seabed of the Baltic.
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Posted: July 23, 2008 at 2:37 pm
Everyone collecting or buying gemstones knows that some are not so hard as others. Gemstone’s hardness in gauged through Mohs scale. On Mohs scale gemstones is ranked on a scale of 1 to 10. It’s also a fact that majority of the people don’t know what Mohs scale does really mean. The hardness of the gemstone is mistakenly considered the key of its durability. In this article, I‘ll try to sort out some confusions about the hardness of gemstone.
To gauge the hardness or resistance against scratch of many minerals, German mineralogist Friedrich Mohs developed a scale in 1822 and later this scale was named as Moh’s scale. This scale was based on ten readily available minerals. Moh scale is a position showing scale and you have to put two minerals on comparison to know what mineral is comparatively hard.
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Posted: July 22, 2008 at 2:11 am
Lapis Lazuli is one of those gemstones as have a long and romantic history. Lapis Lazuli is found at many places ion the world but the best form of it comes from a northern Afghanistan province known as Badakhshan and in this province lapis lazuli has been mined for more than 6000 years regularly.
Lapis lazuli was used as a gemstone material even many thousands years back. Assyrians and Babylonians used it for cylinder seals while ancient Egyptian used it for sacred slabs and amulets. According to many historians, pulverized lapis was used as an eye shadow by Cleopatra. It was also used in buildings and statues, beads, jewelry and many other things.
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