- published: 16 Nov 2010
- views: 3653
Corundum is a crystalline form of aluminium oxide (Al2O3) with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red and padparadscha if pink-orange. All other colors are called sapphire, e.g., "green sapphire" for a green specimen.
The name "corundum" is derived from the Tamil word குருந்தம் "kuruntam" meaning "ruby", and related to Sanskrit "kuruvinda".
Because of corundum's hardness (pure corundum is defined to have 9.0 Mohs), it can scratch almost every other mineral. It is commonly used as an abrasive, on everything from sandpaper to large machines 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 hardness near 8.0.
In addition to its hardness, corundum is unusual for its density of 4.02 g/cm3, which is very high for a transparent mineral composed of the low atomic mass elements aluminium and oxygen.
The day Grandaddy died, she was there by his side
And she held to his hand, till the end
And just before his final breath, the one that took him into death
A smile and tear showed through, like she already knew
And in a voice so low and mild
She stayed and talked a while
Like a friend home form a long long trip
Like a mother to a child
Whenever Grandma got blue, like only widows do
She'd go to their bedroom, and close the door
And for years we thought she prayed, by the bed where he had layed
But we only could assume, what went on in Grandma's room
And in a voice so low and mild
She stayed and talked a while
Like a friend home from a long long trip
Like a mother to a child
(Spoken)
She knew a week before the old barn burned down
And she knew before we told her, when Jack had that wreck in town
And the night before ant Julia passed away, she went over there and stayed
And I finally asked her just how she could know all this
And she just patted my hand and gave me a kiss
And in a voice so low and mild
She said I talked with Jim a while
Like a friend home form a long long trip
Like a mother to a child
Like a friend home from a long long trip
Like a mother to a child