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Rough Corundum

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Original price $3
Current price $2

A lot of rough Corundum with beautiful color and nice size, which can also be used for cutting and faceting purpose. 

Price: $2 per gram

Weight: 450 grams

Origin: Kashmir, Pakistan

Color: Pinkish


The size is bigger than a tablet and smaller than a coin.

 

The color is nice and clarity is also very nice.

 

 

CORUNDUM

Corundum is a crystalline form of aluminium oxide (Al2O3) typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is also a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.

Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost every other mineral. It is commonly used as an abrasive on everything from sandpaper to large tools used in machining metals, plastics, and wood. Some emery is a mix of corundum and other substances, and the mix is less abrasive, with an average Mohs hardness of 8.0.

 

GENERAL

Category

Oxide mineral variety

Formula

aluminium oxide with chromium, Al2O3:Cr

Crystal system

Trigonal

Crystal class

Hexagonal scalenohedral (3m)
H-M symbol: (3 2/m)

Space group

R3c

IDENTIFICATION

Color

Near colorless through pink through all shades of red to a deep crimson

Crystal habit

Terminated tabular hexagonal prisms

Cleavage

No true cleavage

Fracture

Conchoidal, splintery

Tenacity

Brittle

Mohs scale hardness

9.0

Luster

Subadamantine, vitreous, pearly (on partings)

Streak

White

Diaphaneity

Transparent, translucent

Specific gravity

3.97–4.05

Optical properties

Uniaxial/−

Refractive index

nω=1.768–1.772
nε=1.760–1.763

Birefringence

0.008

Pleochroism

Strong: purplish-red – orangy-red

Dispersion

0.018

Ultraviolet fluorescence

Red under longwave