AMIIT SONI(LABORATORY DIRECTOR, IGTLJ)

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Precious: Has beauty, durability, size, and rarity.(Diamond, emerald, opal,ruby,safphire)

Semi-precious: only two of those (quartz, Jade)

A gemstone or gem (also called a precious or semi-precious stone) is a piece of attractive mineral, which when cut and polished is used to make jewelry or other decorations.

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The Mohs Scale characterizes the scratch resistance of different types of minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs.

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Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other

physical properties that have value.Luster: the way light interacts with

the surface of a crystal, rock, or mineral.Sheen.

Greasy LusterGreasy minerals resemble fat or grease. A greasy lustre often occurs in minerals containing a lot of microscopic inclusions. Some examples are opal and cordierite.Many minerals with a greasy lustre also feel greasy or smooth.

Metallic LusterMetallic minerals have the lustre of polished metal.

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Adamantine LusterAdamantine minerals have the best lustre. It is mostly seen in diamond.Diamond minerals are transparent and refract the light the best.Minerals with a true

adamantine lustre are uncommon.

Dull LusterDull (or earthy) minerals have little to no lustre,

because they are coarse and grainy, which scatters light in all directions instead of

reflecting it. These minerals are not used for jewlery or

decorations. http://www.igtlj.com/

Submetalic LusterSubmetallic minerals have similar lustre to metal, but are duller and less reflectiveVitreous LusterVitreous minerals have the lustre of glass. This type of lustre is one of the most commonly seen, and occurs in transparent or translucent minerals

minerals have a luster resembling wax.

Waxy luster

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Pearly LusterPearly minerals consist of thin

transparent sheets. Light reflecting from these layers give them a

lustre similar to Pearls.

Resinous LusterResinous minerals have

the appearance of chewing gum chewing or

plastic

Silky LusterSilky minerals have a parallel

arrangement of fine fibers. This makes the minerals look like silk.

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Magmatic Crystallization: Cooling Magma produces crystals of different kinds of minerals.

Crystals are formed from the lava when the volcano erupts. Examples: moonstone, topaz and corundum.

Metamorphic deposits:

When a rock is in a high temperature and or high pressure, the chemical components get rearranged into new minerals. Gem minerals formed are diopside, corundum,

andalusite, sillimanite, kyanite, epidote, and

garnet. http://www.igtlj.com/

Metamorphic deposits:

When a rock is in a high temperature and

or high pressure, the chemical

components get rearranged into new

minerals. Gem minerals formed are

diopside, corundum, andalusite,

sillimanite, kyanite, epidote, and garnet.

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http://en.wikipedia.org/wiki/Gemstonehttp://en.wikipedia.org/wiki/Lustre_(mineralogy)

http://www.gemstonebuzz.com/gemstone-formation

http://images.google.com/imgres?imgurl=http://www.eoearth.org/media/approved/3/3c/Mohs.jpg&imgrefurl=http://www.eoearth.org/article/Mohs,_Frederick&usg=__wRdbD8V99xE1XCIAy_h-EyRWREE=&h=200&w=149&sz=16&hl=en&start=13&um=1&tbnid=DfUA1xqC7KT6BM:&tbnh=104&tbnw=77&prev=/images%3Fq%3Dfrederick%2Bmohs%26hl%3Den%26safe%3Dactive%26rlz%3D1T4GGLL_enUS355US355%26sa%3DN%26um%3D1

http://www.okaloosa.k12.fl.us/technology/WOWLessons/WOWResources/RockCycleDiagram.gif

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