Rocks, minerals, gemstones mined with surface mining

The dictionary says that a mineral is:  “a naturally occurring … solid substance having a definite chemical composition and characteristic crystalline structure, color, and hardness.” [American Heritage Dictionary]  This means that minerals are formed by nature and are solid.  They are made up of chemicals that form crystals. They are identified by the characteristics that are in all pieces of the same mineral, no matter where it's found.  Some minerals have just one mineral in them, like gold. 

These are called elements and are on a list called The Periodic Table of Elements

Use these links to read the texts about minerals:

Common minerals and metals: uses and importance
The Earth - nature's storehouse
People and Earth's minerals
Dynamic Earth



Task

Here you should publish the information about the rocks, minerals or gemstones that are mined with surface mining. You should describe the mineral characteristics and your experimental data.

For example:

Alexandrite
Mineral characteristics	Mineralogists views	Your conclusions
Chemical Symbol	BeAl2O4	It has aluminum, beryllium, and oxygen in it.
Color	Green or red	In sunlight/fluorescent light the stone is green. In regular light bulb light or candlelight, the stone is red.
Streak	White	When the stone is rubbed on a white plate, it leaves a white dust. If the stone is crushed, this is what color the powder would be.
Transparency	Transparent to translucent	You can see through some stones and others are blurry to look through.
Luster	Glassy	It shines like glass.
Cleavage	Imperfect	If you break this mineral, it will not split smoothly and evenly.  You can’t break it over and over again and get the same shaped pieces.
Fracture	Conchoidal	The stone has a smooth, shell-like surface when it is broken.
Magnetism	None	It will not attract or be attracted to a magnet.
Hardness	8.5	The stone is hard. It will scratch the streak plate that you test it on.  It would also scratch a nail!
Specific gravity	3.5	If you held it, this stone would seem a little bit heavier than its size would make you think it would be.
Crystal shape	Orthorhombic