[Vwdiesel] Rabbit droppings # 123 -- ( the back to school geezer )

[H.Hagar]

72 and still a student ?   you bet your ass -----

I sat for a long time this morning  trying to find words to describe how much
fun and downright rapture it is for me to  get EDUCATED.    NO words were
adequate.
The smarts you get in the cradle   the information you get in school.     Combine
the two to critical mass ---and stand back ..   The sky is not the limit ---
there is NO limit.   IMHO  there never will be.
Here is a sample lesson I got from Doyt Echelberger :

Abrasives 101. :
Note: Diamonds are 4 times as hard as corundum, but corundum is still very 
hard, and the second hardest material available.

OK, now is a good time to talk about the benchmark....diamonds:

In terms of it's physical properties, diamond is the ultimate mineral in 
several ways:
·       Hardness: Diamond is a perfect "10", defining the top of the 
hardness scale.
·       Clarity: Diamond is transparent over a larger range of wavelengths 
(from the ultraviolet into the far infrared) than is any other solid or 
liquid substance - nothing else even comes close.
·       Thermal Conductivity: Diamond conducts heat better than anything - 
five times better than the second best element, Silver!
·       Melting Point: Diamond has the highest melting point (3820 degrees 
Kelvin)!
·       Lattice Density: The atoms of Diamond are packed closer together 
than are the atoms of any other substance!
WHAT ARE THE PHYSICAL CHARACTERISTICS of DIAMONDS?

·       Color is variable and tends toward pale yellows, browns, grays, and 
also white, blue, black, reddish, greenish and colorless.
·       Luster is adamantine to waxy.
·       Transparency crystals are transparent to translucent in rough 
crystals.
·       Crystal System is isometric; 4/m bar 3 2/m
·       Crystal Habits include isometric forms such as cubes and 
octahedrons, twinning is also seen.
·       Hardness is 10
·       Specific Gravity is 3.5 (above average)
·       Cleavage is perfect in 4 directions forming octahedrons.
·       Fracture is conchoidal.
·       Streak is white.
·       Associated Minerals are limited to those found in kimberlite rock, 
an ultramafic igneous rock composed mostly of olivine.
·       Other Characteristics: refractive index is 2.4 ( very high), 
dispersion is 0.044, fluorescent.
·       Notable Occurrences include South Africa and other localities 
throughout Africa, India, Brazil, Russia, Australia, and Arkansas.
·       Best Field Indicator is extreme hardness.
PHYSICAL CHARACTERISTICS of CORUNDUM:

·       Color is highly variable. The color can be white or colorless, 
blue, red, yellow, green, brown, purple, and pink; there are also instance 
of color zonation.
·       Luster is vitreous to adamantine.
·       Transparency: Crystals are transparent to translucent.
·       Crystal System is trigonal; bar 3 2/m
·       Crystal Habits include sapphire's typical six-sided barrel shape 
that may taper into a pyramid, and ruby's hexagonal prisms and blades.
·       Cleavage is absent, although there is parting which occurs in three 
directions.
·       Fracture is conchoidal.
·       Hardness is 9
·       Specific Gravity is approximately 4.0+ (above average for 
translucent minerals)
·       Streak is white.
·       Associated Minerals include calcite, zoisite, feldspars, micas and 
garnets.
·       Other Characteristics: Refractive index is around 1.77; pleochroic 
(meaning color intensity is variable from different viewing directions); 
striations on parting surfaces.
·       Notable Occurrences include Burma; Sri Lanka; North Carolina and 
Montana, USA; many African localities; several localities in India, and 
Middle Eastern and Southeast Asian countries.
·       Best Field Indicators are extreme hardness, density and crystal habit.

And, since emery is a mixture of corundum and magnetite, we should examine 
the properties of magnetite (magnetic iron oxide):

Magnetite: Chemical Formula: Fe3O4, Iron Oxide.

Magnetite is a natural magnet, hence the name, giving it a very nice 
distinguishing characteristic. Explaining the magnetism is not easy but 
here is a go at it. Remember, electricity produces magnetic fields just as 
magnetism produces elecrtic fields. Magnetite is a member of the spinel 
group which has the standard formula A(B)2O4. The A and B represent usually 
different metal ions that occupy specific sites in the crystal structure. 
In the case of magnetite, Fe3O4, the A metal is Fe +2 and the B metal is Fe 
+3; two different metal ions in two specific sites. This arrangement causes 
a transfer of electrons between the different irons in a structured path or 
vector. This electric vector generates the magnetic field.
  
There you go ? EH ?   Emery paper in the bad old days used MAGNETITE.

Hagar.   PS : Class dismissed.