Blue obsidian?

Hi there,
Today I got a blue obsidian in the package I received from lovely bodhran (thanks a lot!!!). I know of the poperties of golden, snowflake, rainbow and mahagony obsidian but now I am wondering:

a) where does the blue obsidian gets its colour from?

b) what are the special poperties of blue obsidian?

Thanks in advance.

Catlin,
Here's some stuff I pulled from various places:

Obsidian is a volcanic glass formed by rapid cooling. It is often called 'rock glass' or ''volcanic glass' due to the fact that that it is created so quickly that there is no time for facets to be formed.
Blue obsidian cannot be used for evil. This is the protection stone for sensitive or psychic people. It provides a wonderful screen against negative energy and is good for balancing the digestive system.
Blue obsidian, as well as having the general properties of obsidian, stimulates the throat chakra. An excellent stone for someone who has to speak in public, it enhances communication. It is said to aid telepathic skills and act as a protector during traveling.It is good in relieving eye problems, it assists with speech therapy and alleviates pain. It can also assist mental clarity with disorders such as Alzheimer's disease, schizophrenia and multiple-personality confusion.
The color of obsidian varies depending on the presence of impurities.

Many pieces sold as blue obsidian are man-made. For instance these crystal skulls are carved from man-made "blue obsidian":
http://www.soul2shine.com/shop/section.php/23/0/0924b6e5aad0f086b4a6502e6dcd66a3

Many blessings,
Bodhran

bodhran said:

Obsidian is a volcanic glass formed by rapid cooling. It is often called 'rock glass' or ''volcanic glass' due to the fact that that it is created so quickly that there is no time for facets to be formed.

Click to expand...

It's also sometimes referred to as "volcano spit." (Not a pleasant little image, but one I thought interesting.)

Thanks, bodhran and sharpchick for the additional information.

I have placed the blue obsidian in my medicine bag I carry with me when I do ritual work.

Real obsidian is black, grey or brown. Only. Glass comes in many colors.

Obsidian colors

wizzle said:

Real obsidian is black, grey or brown. Only. Glass comes in many colors.

Click to expand...

I'm sorry, could you explain your post? Obsidian is volcanic glass, not a real mineral, per se, so could you eplain what you are calling 'real' obsidian? Yes, it does come in colors, mainly caused by refraction. Blue, purple, rainbow, silver sheen, gold sheen, and even electric blue are all colors of obsidian. For more info on obsidian, please go here:

http://www.mindat.org/min-8519.html

I would appreciate more information on obsidian, if you have any links that explain your use of the word, it would be appreciated.