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Corundums
Corundum is a crystalline form of aluminium oxide, with impurities or trace elements such as iron, titanium, or
chromium. These impurities are what create the wide range of colors to be found in corundum crystals: grays,
browns, yellows, greens, blues, purples, reds and pinks. It is a naturally transparent material, but can have
different colors when impurities are present. Transparent specimens are used as gems. Corundum is best
known for its gem varieties, Ruby and Sapphire. A corundum crystal that is red is called a ruby. All other colors
are called sapphires. Sapphires that are not gem variety are simply referred to as corundums. The name
"corundum" is derived from the Tamil word (from India) Kurundam which originates from the Sanskrit word
Kuruvinda meaning ruby.

Corundum is a very hard, tough, and stable mineral. It is the second hardest mineral after Diamond. It is
unaffected by acids and most environments. Translucent brown and emery are the most common forms of
corundum, and due to their hardness and availability are used as abrasives. The term "emery" such as “emery
cloth” comes from the corundum variety “Emery” which is mined specifically for its use as an abrasive. Erosion
may cause Emery to crumble and form what is called "black sand."
The most common varieties of corundum        
Emery - Black, massive variety of Corundum, with color from Magnetite, Hematite, and Spinel.
Padparadschah - Orange-pink gem variety of Sapphire (A very rare and sought after variety)
Ruby - Red variety of Corundum
Sapphire - Refers to all gem varieties of Corundum, except the red variety
Star Ruby - Ruby displaying asterism in the form of a six-rayed star.
Star Sapphire – a Sapphire displaying asterism in the form of a six-rayed star.

Corundums are found in Burma (Myanmar), Sri Lanka, (The finest and largest crystallized specimens of gem-
quality Sapphire are from Sri Lanka) Thailand, Vietnam , Afghanistan, India, Africa, Madagascar, Tanzania and
Canada. In the U.S.A. they are found in Montana, California, North Carolina, New York, and Massachusetts. A
well-known Ruby locality is the Cowee Creek District, Macon Co., North Carolina, especially the area of Franklin.
Large deposits of Emery were found in New York and Massachusetts.
Common Minerals found with Corundum are Calcite, Albite, Muscovite, Spinel, Almandine, Kyanite
Corundum can be confused with many minerals, particularly the silicates, but the high hardness and specific
gravity of Corundum can easily distinguish it from any mineral. Some corundums are SW Fluorescent.

Ref. http://www.minerals.net/mineral/corundum.aspx,  https://en.wikipedia.org/wiki/Corundum,  http://www.mindat.org/min-1136.html,  
https://www.gemsociety.org/article/distinguishing-rubies-pink-sapphires/
Item # 1CRNDS01174754
High Grade Rare Ruby Pink
Fluorescent Sapphire from
India

$95.00
Here's an excellent multi crystal mass formation of one of the most fluorescent types of Ruby/Sapphire Crystal
Clusters ever found in India. Purple Pink sapphire in matrix. Sapphire has strong SW fluorescent red glow.
specimen weighs 7.8 oz or 0.49 lbs (222g) and measures 3.4 x 1.8 x 1.2 inches (8.6 x 4.7 x 3.2cm)
Item # 2CRNDS01179927
High Grade Rare Ruby Pink
Fluorescent Sapphire from
India

$199.00
Here's an excellent multi crystal mass formation of one of the most fluorescent types of Ruby/Sapphire Crystal
Clusters ever found in India. Purple Pink sapphire in matrix. Sapphire has strong SW fluorescent red glow.
specimen weighs 21 oz or 1.31 lbs (597g) and measures 4.1 x 2.8 x 2.2 inches (10.6 x 7.2 x 5.7cm)
Item # RUBZ01176495
Ruby in Zoisite aka Anyolite  
from Africa

$120.00
Ruby in Zoisite, also called Anyolite, is a combination crystal that contains both the properties of fiery Ruby and
earthy Zoisite. A metamorphic rock known as anyolite consists of green zoisite with black tschermakite and red
ruby crystals.
specimen weighs 17.3 oz or 1.08 lbs (490g) and measures 43 x 2.6 x 2 inches (7.7 x 6.7 x 5.2cm)