is a Sodium Aluminum silicate +sodium chloride with general formula Na 8(Al 6Si 6O 24)Cl 2 and hardness of 5.5-6. In this case it contain a minor quantity of K.
Is a very common mineral in it's opaque form,but become rare when is translucent or transparent.It can be of various colors: from white to grey,pink,brown,blue,purple and colorless..When is transparent the crystals are usually very small. A tenebrescent variety is called Hackmanite.
Is fluorescent at short wave.
This piece comes from Afghanistan.