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Mineralogy

min' er al, a natural inorganic substance of definite chemical composition and usually of definite crystal structure

CONTENTS
How Atoms are Arranged in Minerals
How Atoms are Arranged in Minerals
To imagine what it is like inside a mineral crystal, you can think of "rooms" formed by the crystal's atoms.
Why Some Minerals Cleave
Why Some Minerals Cleave
The Mohs Hardness Scale
Agate
Agate
forms when silica in solution seeps into a cavity in lava and hardens in successive layers. Its chemical formula is SiO2.
Amber
Amber
is the fossilized resin of pine trees that grew millions of years ago. It often contains insects or other small animals, feathers, plant materials, etc. that were trapped as the resins flowed from the trees, and some pieces even contain air bubbles. Known as inclusions, these "imperfections" often increase the value of a piece of amber.
Corundum
Corundum
is a transparent to translucent mineral which is found in several colored -- white, blue, red, yellow, green, brown, purple, and pink -- as well as in colorless forms. Chemically it is alumina, or aluminum oxide, Al
2O2.
Cullinan Diamond
Cullinan Diamond
The largest clear white diamond ever found, the Cullinan weighed an astonishing 3,106.75 carats before being cut into 9 major (the largest of which weighs 530.2 carats) and 96 minor individual diamonds.
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