Hematite Diamond

Hematite Diamond

Corundum is the second hardest natural mineral known to science.

The History Says

One century ago, the richest corundum mine in the world was in Canada, at Craigmont, located several kilometres south of Combermere, Ontario, in the woodsy hill country of Raglan and Carlow Townships.

Corundum is a very interesting mineral. It is an exceptionally hard aluminum oxide that forms in igneous and metamorphic rocks. It is primarily used as an abrasive. Corundum is also one of the most popular minerals - rubies and sapphires are colored corundums. Rubies are deep red corundums of gemstone quality. Gemstone quality corundums of any other color are sapphires.

Hardness and Use as an Abrasive

Corundum is very hard. It is the standard mineral for a Mohs Scale hardness of nine. It is the second hardest mineral known, with diamond being the only harder mineral.

This high hardness makes corundum especially useful as an abrasive. Crushed corundum is screened to produce uniformly-sized grits and powders which are used as grinding media and to manufacture polishing compounds, sand papers, grinding wheels and cutting tools.

Emery

Emery is a granular metamorphic or igneous rock that is rich in corundum. It is a mixture of oxide minerals, typically corundum, magnetite, spinel and/or hematite. It is the most common form of natural corundum used to manufacture abrasives.

Red Corundum: Ruby

Most corundum occurs as white, gray, dull blue or dull red crystals. However, a very small amount of corundum has a transparency, purity and color that make it suitable for use as a gemstone. These colorful corundums are among the most popular and valuable gems.

Some gem-quality corundum is contaminated with trace amounts of chromium. A very small amount of chromium gives corundum a pink color and larger amounts produces stones that are deep red. These deep red corundums are known as ""rubies"". Transparent rubies are cut into faceted stones and translucent rubies are cut into cabochon-shaped gemstones.

Blue Corundum: Sapphire

Corundum that is contaminated with iron or titanium has a blue color. Deep blue corundums are known as ""sapphires"". When used alone, the word ""sapphire"" always refers to a deep blue corundum.

Gem quality corundum occurs in a wide range of colors, including pink, pale blue, yellow and green. These stones are also known as ""sapphires"", however, when the color of a sapphire is any color other than deep blue the color of the stone is always used as an preceding adjective. For example: pink sapphire, yellow sapphire, green sapphire. Used alone, the word ""sapphire"" refers to the deep blue corundum.

The color of corundum can be artificially altered by heating or radiation. Sometimes cloudy or translucent stones can be heated to yield brighter color or more transparent stones. When these color treatments are done the stone is supposed to be labeled as ""heat treated"" when it is presented for sale.

Mining Rubies and Sapphires

Most gem-grade corundums form in metamorphic rocks such as schists or igneous rocks such as syenite. However, they are rarely mined from the rocks in which they form. Instead, they are usually mined from stream sediments. Rubies and sapphires are very hard and that enables them to survive the abrasive actions of a stream. Their high specific gravity, relative to other sediment particles, often causes currents to concentrate them in small deposits. Most rubies and sapphires are produced by washing the gravels of these stream deposits.

Corundum Occurrence

Corundum is found in igneous rocks such as syenite, nepheline syenite and pegmatite. It is found in the rocks of contact metamorphism and in mica schist, gneiss and marble. Because it is very hard and chemically resistant, corundum is also found in alluvial deposits.

Synthetic Corundums

Natural deposits of corundum are often impure and not available in large quantities where it is needed for manufacturing abrasives. This need is often met by producing synthetic corundum from bauxite. The synthetic corundum is of high quality and cost competitive with natural sources.

Synthetic rubies and sapphires are also produced. The manufacturing process can produce large, flawless single crystals which can be cut into attractive gemstones. The color in these stones can be controlled by adding small amounts of chromium, titanium or other substance. Special optical effects such as asterism can be imparted to the stones by adding titanium or another material which crystallizes in the form of needles (such as rutile). These needles can be in alignments which produce a ""star"" appearance when the stones are cut and polished. The synthetic stones are to be labeled when sold and it is often difficult for even an expert to distinguish them from natural stones.

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Article Source: ArticlesBase.com - Corundum Mineral

• Aventurine

-. A healing stone, provides emotional, stimulates creativity.

Agate

- The garden stone, gives protection and self confidence.

Alexandrite

-. Da luck and love, brings renewal and regeneration .- Stone thought, stimulates the mind

Amber

- The energy stone, protects and heals

Amethyst

- Bring tranquility, rises, gives a feeling peace

Apatite

- Calm, relieves guilt

Aquamarine

- The exposed stone, improving the senses, calm

Aragonite

- The truth of stone

Azurite

-- The stone of meditation, relieves joint pain

Bloodstone

- The value and stone healing.

Carnelian

- Stone Energy, catering to the mind and spirit.

Chalcedon

- Increases vitality, endurance, helps your eyes, fevers

Chrysocolla

- Soothing, relaxant, to relieve stress

Chrysoprase

- Give peace and welfare, help with depression

Citrine

- Bring the energy, healing

Coral

- Protection against evil

Diamond

- Succcess brings removes evil

Esmeralda

- Help with memory, improves mental clarity

Fluorite

- Bring balance, peace, harmony

Garnet

- Stone of truth, brings peace, sexual desire

Gaspeite

- Stone of Healing, reduces stress, brings spirituality

Goldstone

- To relieve stress, brings peace of mind, calm

Hematite

- Reduce stress, bringing balance, soothing

Howlite

- Soothing, calming, bringing balance

Jade

- The dream of stone, protects against nightmares and evil

Jasper

- Bring peace and welfare to mind, calm

Red Jasper

- Help with poise and elegance

Leopard Skin Jasper

- Stone of positive energy

Picture Jasper

- Bring balance and peace, good stone for meditation

Labradorite

- Brings inner peace, calm the conflicts of the mind

Lapis Lazuli

- Bring peace and clarity to the mind

Malachite

- Bring the protection from evil, protects against negativity

Meteorite - Bring purity, increased iron, resistance

Moonstone

- The stone of love, promotes love and welfare

Morganite

- The stone of compassion, brings calm and well being

Onyx

- Protects against negativity, promotes peace,

Opal

- The stone of the mystic, help with intuitive powers

Pearls

- Brings wisdom, safety, love bearer

Peridot - The stone of balance, helps with digestive problems

Quartz

- The healing stone, helps with emotional illness, physical and mental.

Rose Quartz

- The stone of love, helps attract love and happiness.

Smoky Quartz

- Relieves sadness - Brings mental clarity and peace of emotional problems

Rhodonite

- Promotes emotional well-being and self

Ruby

- Protects against negativity, helps relieve physical ailments.

Sapphire

- The stone of purity, provides sense of accomplishment, reduces negative thinking.

Sardonyx - relieves anxiety, soothes nerves

Snowflake Obsidian

- The stone of protection, bringing emotional peace.

Sodalite

- Protects against negativity in your immediate area.

Tanzanite - The power comes to intuition, clarity of stone

Tiger Eye

- The stone of confidence

Topaz

- Stone calming, promotes self confidence

Tourmaline

- Driving self-confidence, calm, protects against negative people.

Turquoise

- The stone of friendship, relieves guilt, brings peace of mind ..

Unakite

- Brings emotional, calm, protects against negativity

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Article Source: ArticlesBase.com - Gemstones and Their Folklore - Jewelry Making