I need help with the gem Amethyst.?

Question

I can't seem to find the chemical composition/formula, it's streak, shape, specific gravity/density, or how it's mined. Could you please help me?

Answer 1

Its chemical composition is very similar to quartz but it contains low levels (few parts per million) of Manganese which gives it the purple colour. The crystal structure is trigonal - same as quartz as is the streak and specific gravity (2.65grams per cc). It forms by crystallising from water saturated with dissolved silica and metals in cavities in rocks (the same process by which salt will crystalise out from solution in water when it becomes saturated).
Its mined usually by hand (expolisves etc. would destroy it !) with pickaxes and shovels. It occurs as rounded lumps called geodes which have the amethyst inside them.

Coincidentally, if you heat treat Amethyst it can turn a sort of dirty yellow so it looks a bit like Citrine but its nowhere near as good as natural Citrine. That doesn't stop people selling it though !

Also Amethyst fades slowly in daylight, but the colour can be restored by irradiating it with x-rays.

And NO no No Quartz isn't hexagonal. Everyone makes that mistake just cos its six sided. Its Trigonal.

By the way, the name Amethyst has a Latin root - the Romans believed it guarded against drunkeness. A-methyl.

Answer 2

Excerpts from Wikipedia...
Amethyst (SiO2) is a violet or purple variety of quartz often used as an ornament.

Quartz is one of the most common minerals in the Earth's continental crust. It belongs to the hexagonal crystal system, and is made up of silicon, (SiO2), tetrahedra. Quartz has a hardness of 7 on the Mohs scale. Density is 2.65 g/cm³. The typical shape is a six-sided prism that ends in six-sided pyramids, although these are often twinned, distorted, or so massive that only part of the shape is apparent from a mined specimen. Additionally a bed is a common form, particularly for varieties such as amethyst, where the crystals grow up from a matrix and thus only one termination pyramid is present. A quartz geode consists of a hollow rock (usually with an approximately spherical shape) with a core lined with a bed of crystals.

General
Category Mineral (Quartz)
Chemical formula (or Composition) Silica (silicon dioxide, SiO2)
Identification
Color Clear (if no impurities); also see Varieties
Crystal habit 6-sided prism ending in 6-sided pyramid (typical)
Crystal system Hexagonal
Cleavage None
Fracture Conchoidal
Mohs Scale hardness 7 - lower in impure varieties
Luster Vitreous/glossy
Refractive index 1.544-1.553 - DR +0.009 (B-G interval)
Pleochroism None
Streak White
Specific gravity 2.65 constant; variable in impure varieties
Melting point 1650 (±75) °C
Boiling point 2230 °C
Solubility H2O insoluble

Hope this helps!

Answer 3

Kelly C. is correct, further information can be found on the web. Search for Four Peaks Amethyst mine, Arizona.

Answer 4

Hi. I believe it is simply quartz with some specific impurities. Try this link : http://www.answers.com/main/ntquery?s=Amethyst&gwp=16

Answer 5

tricky aspect. try searching on google or bing. that will could actually help!