Aventurine is a type of quartz characterised by minute "platy" inclusions. This describes tiny inclusions of other minerals that are often shaped like a plate.
The most common colour which is green comes from the presence of fuchsite, mica or hematite.
It can also be found in pink, blue, yellow, orange and several other colours.
Blue and green aventurine comes mostly from India. Other colours can be found in Spain, Chile and Russia.
The sparkly appearance that can often be seen in aventurine is known as aventurescence. It's caused by the reflection of light off minute inclusions.
Aventurine is believed to have been named after the manmade material known as goldstone.